Stellar Blade Online 0.9.0

0.9.0 (2026-11-09)

Both players need 0.9.0 and Stellar Blade's Steam build 26123051.

Game update

• Steam's update of Stellar Blade on 2026-11-05 (build 26123051, the Bayonetta collaboration) moved every address the
  mod reads in the game. This version is ported to that build and does not run on the old build 24463856.
• 0.8.0 does not run on the new build: its native part turns itself off (coop status shows engine=off), so the
  partner's movements, shared fights, shared quests and the co-op saves stop working.
• The link protocol stays 19. A player on 0.8.0 can still join a 0.9.0 session, but with the native part off, so
  both players should update.
• Checked on one PC on 2026-11-09: the native part starts on the new build, the co-op saves switch on and load, and
  every table row the mod adds goes in with none refused. It has not been played between two PCs on this build yet.

Documentation

• The README and the guides are split into one page per subject, with an index in docs/README.md and the technical
  pages under docs/internals/.

Report problems on the Discord with coop-report.txt, coop-link.log and UE4SS.log.

Stellar Blade Online 0.8.0

Since 0.7.5

Both players need 0.8.0: the link protocol changed (19), so it cannot play with 0.7.5 or older.

Teleport screen

• The between-regions teleport screen now shows up to 9 regions. The game's screen has 7 tabs and leaves out every
  active Tetrapod past the 7th; the mod adds 2 tabs after them, in the game's order. With 9 tabs, a bar under the row
  scrolls it. After coop off the screen goes back to its 7 tabs.

Stability

• After a travel or a load, the mod no longer reuses game objects from the previous map in four places: flying with
  coop fly, the camp booth scan after a return to the title screen, the cutscene check during a session, and your
  friend's ghost after your EVE changes. An object reused this way crashed the game during testing on 2026-11-03, in
  the Matrix XIII ladder code, which only runs on the test map; an audit then found these four.

Ghost

• UE4SS.log now names every part of your friend's outfit that falls back to the base suit because its mesh has no
  skeleton, game paths included, not only CNS parts.

Commands

• coop near [metres] lists the zone objects the game spawned around EVE (8 m by default, 100 at most), nearest first,
  with their row and state. It is a test tool, mainly for the Matrix XIII map.

Matrix XIII

• Work on the cut Matrix XIII dungeon (Lily's signal, the On Time quest, the four zones and their talks) continues in
  this version, but it needs a test map that is not part of this release, so none of it shows in your game yet.

Not run in game yet: tabs 8 and 9 holding a region, and the four stability fixes.

Already in 0.7.5 (for players coming from 0.7.0-beta.1)

Ghost

• Joining a friend no longer crashes the game when one of their CNS meshes has no skeleton on your PC. That part now
  shows on the base suit, or is left out, and UE4SS.log names the mesh with "has no skeleton".
• CNS colours and options now show on your friend's screen: hair colours, eye and face tints, weapon glow and the other
  values CNS sets on an outfit's materials. A texture option shows only when your friend's own CNS packs hold that
  texture. On a game mesh (the base hair, face or suit), these values show only when both players have dyes=on in
  coop-settings.txt, or after coop look dyes on.
• CNS options that hide parts of an outfit now show too: piercings, tattoos, moles and the other face or outfit options.
• A change of colour or option reaches the ghost within about 20 s at worst.

Mods and crashes

• If a CNS or mod asset crashes the game while it is drawn on your friend's ghost, the mod sets that asset aside at the
  next launch: the part then shows on the base suit, and a notice names it. coop cns shows the list and
  coop cns reset clears it.
• A Lua error in the CNS part of the ghost no longer stops the ghost: it is rebuilt without its CNS parts, and the link,
  the shared fight and the quests keep running.

Effects

• With effects=on on both PCs (coop look effects on), the ghost shows effects from the game's FX folders beyond the old
  list of 19, and assets from a mod both players have (same pak name and size), with mod_names=on, the default.

Known issues

• CNS face shape keys do not show on the ghost.
• An outfit table over 56 KB is sent without its values, and the ghost then shows the plain materials.

Report problems on the Discord with coop-report.txt, coop-link.log and UE4SS.log.

Stellar Blade Online 0.7.5

Since 0.7.0-beta.1

Both players need 0.7.5: the link protocol changed (18), so it cannot play with 0.7.0-beta.1 or older.

Ghost

• Joining a friend no longer crashes the game when one of their CNS meshes has no skeleton on your PC. The game crashed with an access violation while drawing the friend's ghost; one player hit it twice with CNS on. That part now shows on the base suit, or is left out, and UE4SS.log names the mesh with "has no skeleton". Tested between two PCs on 2026-11-01: no crash since.
• CNS colours and options now show on your friend's screen: hair colours, eye and face tints, weapon glow and the other values CNS sets on an outfit's materials. The mod reads them from your materials and sends them with your outfit, and your friend's ghost applies them. A texture option shows only when your friend's own CNS packs hold that texture.
• On a game mesh (the base hair, face or suit), these values show only when both players have dyes=on in coop-settings.txt, or after coop look dyes on. On a mod's mesh they show with dyes off too.
• CNS options that hide parts of an outfit now show too: piercings, tattoos, moles and the other face or outfit options CNS turns on and off.
• A change of colour or option reaches the ghost within about 20 s at worst. A table that only changes values goes out at most once every 5 s.

Mods and crashes

• If a CNS or mod asset crashes the game while it is drawn on your friend's ghost, the mod notes it before the call and sets that asset aside at the next launch: the part then shows on the base suit, and a notice names it. coop cns shows the list and coop cns reset clears it. The list also clears when the mod version changes.
• A Lua error in the CNS part of the ghost no longer stops the ghost: the ghost is rebuilt without its CNS parts, and the link, the shared fight and the quests keep running.

Effects

• With effects=on on both PCs (coop look effects on), the ghost now shows effects from the game's FX folders that were not on the old list of 19, for example the Raven and Scarlet effects that GodEmpress (queen-lite) plays. Your friend does not need the mod for those.
• The ghost can also load assets from a mod both players have, with the same pak name and size, such as GodEmpress's Tachy blades. It works with mod_names=on, the default, on both PCs.

Known issues

• CNS face shape keys do not show on the ghost: the engine does not draw them on the kind of part the ghost is made of.
• A very large outfit table, over 56 KB, is sent without its values, and the ghost then shows the plain materials.

The crash fix ran in game. The CNS colours and options, the crash sentinel and the new effects have not run in game yet. Report problems on the Discord with coop-report.txt, coop-link.log and UE4SS.log.

Stellar Blade Online 0.7.0-beta.1

Since 0.6.0-beta.3

Both players need 0.7: the link protocol changed (14), so 0.6 and 0.7 cannot play together. A friend on 0.6 cannot join a 0.7 session.

Most of this release has not run in game. Solo sessions on 2026-10-27 and 2026-10-28 covered the switch to the co-op saves, the Night Operation shop screen, camp travel in and out of Matrix XIII, and Roxanne in Xion; the Roxanne and shop fixes below came after them. On 2026-10-28 two PCs (Linux and Windows, about 90 ms apart) linked on protocol 14 for six minutes: the link and the ghost worked, with no packet lost; the other co-op features did not run. Back up your saves before you try it.

Link

• When the queue to your friend stays at 100 ms or more, or 64 KiB or more waits to go out, the mod sends 30, then 20 poses a second instead of 60. It steps back up one level after 10 calm seconds (queue under 20 ms and under 16 KiB waiting). When a step up has to be undone, the next wait doubles, up to 80 s. Each step writes a line to coop-link.log.
• Bone changes of only a step or two of the encoding are no longer sent between keyframes. On two synthetic recordings this cut the pose data by 14 and 20 %. It has not been measured on a recording from the game.
• The outfit table goes to a new friend at once, then 5, 10, 20, 40 and 60 s apart while nothing changes, instead of every 5 s. An outfit change still goes out at once. If her game loses the table, your ghost on her screen can stay missing or in its old outfit for up to 60 s, where it was 5 s before.
• The mod's camp travel and the friend revive no longer stall on the game's respawn state. Since 0.5.0-beta.1 the mod read the at-rest value as a respawn in progress, so it refused every camp travel as "respawn" and never asked for the friend revive. Since the fix, one travel has arrived in game (coop mxiii, after a save reload). coop travel probe and the revives have not been tried.
• coop travel probe now goes only to camps your save has activated (the activated= line of coop status).
• A pause of more than about 1 s now ends the shared fight, and a new one starts when the game resumes. The enemies pair again: the guest's copies unfreeze, and the HP scale and boss mode go off and come back on.
• Same place no longer looks enemies up while the game runs a logic task. With shared quests on (experimental, off by default), a reload no longer hands the guest every quest step of the host. A looping ambient scene no longer freezes the game for a frame every second while linked.
• A second Select on Leave or Remove in the co-op menu can no longer run another row. Doro races no longer end in a teleport DNF after a streaming hitch, and backward speed no longer runs away.

Night Operation

• Runs and challenges never tracked their monsters in 0.5 or 0.6, so kills did not count and runs paid nothing. Runs on 2026-10-26 and 2026-10-28 tracked 0 of every wave although the monsters appeared and fought: the mod only kept bodies whose state read 0, and the bodies its spawn makes read 1 while they live (3 once dead). A monster now counts as standing at state 0 or 1, and as killed at 3. Not tested in game yet.
• Wave monsters no longer appear inside walls: each spawn point is moved onto the navmesh in the open before the spawn, pulled back from a wall or moved to a free gate, and the spawn line in UE4SS.log says how it moved ("ground: moved 6.5 m", "ground: gate 3 blocked, gate 2"). If the game's navigation calls do not answer, the run spawns as before and the first spawn line says "ground: unchecked". Not tested in game yet.
• coop nightop start easy, normal, hard or nightmare sets the number of monsters (15 to 40, 20 at normal), the time limit and the points. Monster HP and damage do not change with the level.
• In a co-op run where the downed player has revive=on (Options > Session > Friend can revive me, off by default), a death is a down of 30 s instead of the end of the run. Your partner revives you by holding the interact key (F or the right trigger) for 3 s next to your EVE, or you get up yourself with coop nightop revive: 3 times a run at easy, 2 at normal, 1 at hard, none at nightmare. The game's in-place respawn this uses has not run in game yet.
• coop challenge range is the Shooting Range, solo or started by the host for both players.
• The run result shows the guest's own best.
• coop nightop shop opens the game's own shop screen, with your points shown as the cut Beta Seed. It opened in game with 0 points; nothing has been bought from it yet. If the game is paused when the screen is about to open (Escape that closes the console also opens the pause menu), the open now waits up to 30 s for the game to play instead of giving up. coop nightop buy lists the items and buys by number. It no longer stops every purchase on EVE's ID (checked in game on 2026-10-26), but no purchase has gone through in game yet.
• Three cut items are for sale: the Burst Stimpack, the Beta Stimpack and the Shock Bolt ammo for EVE's gun. None has been bought, used or fired in game yet. EVE carries 30 Shock Bolts at most, and coop nightop buy 7 still charges for bolts above 30, which are dropped.
• On a co-op save, Roxanne in Xion offers Night Operation at easy, normal or hard, and its supplies, among her choices. The mod writes the four labels straight into the borrowed dialogue rows in the game's current language. A run booked there starts once you are out of Xion with no one within 40 m; in a session only the host's pick books a run. A first version registered the labels through an engine call that fails in this UE4SS build (see below); the fixed version has not run in game yet.

New commands

• coop gift sends 1 to 10 of seven consumables (potions and grenades) to your linked friend, who takes them with coop gift take. A refused or unanswered gift comes back to you. Both players need a co-op save. Not tried in game.
• coop emote asks the game's own animation call to play one of 39 clips on EVE: photo-mode poses, two waves and six clips made for two enemies missing from the game files. Nobody has checked in game yet that the clips show.
• coop fly on (co-op save only) should start the developer flight at the third press of the space bar in the air, fly level, and climb and descend with eased speed. This version has not run in game, and earlier versions of the third press and the level flight failed there. coop glide on brings back EVE's cut glide while Jump is held (not tried in game).
• coop devmenu runs 20 rows of the game's developer menu that should still work, and coop devinfo opens its quest debugger or player panel. coop chainspin asks for EVE's cut Tachy Mode ChainSpin. None of these has been tried in game.
• coop gardener fight and coop tendril fight spawn two cut Naytibas as enemies, with the table rows they lack added in memory. Not tried in game.
• coop shortcut lists the 15 developer saves of the cut Load Shortcut menu. coop shortcut load replaces co-op slot 5 (StellarBladeCoop04.sav, backed up first in StellarCoopBackups) with one of them. It is off unless shortcut_load=on, because those saves can unlock Steam achievements for good: use it only on a Steam account whose achievements do not matter, with Steam Cloud off. Not tried in game.
• coop lines enya plays seven voice takes the game never uses. coop orcal show preview shows Orcal's test mesh.
• coop mxiii is a research tool for the cut Matrix XIII dungeon. It needs a test pak that the mod does not include, and without it the command refuses.

Saves and stability

• With auto_coop_save=always, the switch to the co-op saves is asked again at game start, up to three times, when the first ask gets no answer. The default (ask) is unchanged. This retry has not run in game yet.
• coop saves export N M, typed twice within 10 s at the title, writes co-op save N over your save M after backing up M. Both are file numbers from 0 to 4, so the game's first slot is 0 and co-op slot 5 is 4. It refuses a save that holds the mod's items, names the Matrix XIII dungeon or came from coop shortcut load. Restart the game afterwards. Not tried in game.
• Most parts of the mod now run on their own: an error in one is logged once with its traceback, and the others keep running. coop off finishes even if the ghost's removal fails.

Known issues

• coop recruiter's lines and the subtitles of coop scene emil stay in Korean (Japanese for some scene lines). UE4SS 3.0.1 cannot pass a translation table inside a structure to the engine: it reads the wrong table, and depending on the order Lua walks it, it could write over memory. The mod therefore no longer calls it, and logs "STOP: text: this UE4SS build cannot pass a Lua table as a map inside a struct parameter".
• Roxanne's labels follow a change of the game's language only at the next Lua load or when her choices are armed again.
• After a game restart, the game has no rows for the Shock Bolt, the two cut stimpacks and the Beta Seed until your next coop nightop shop or your next buy of one of them. Nobody has tried how the game loads a save that holds one of these items without its row. Use up the stimpacks and bolts before you save. Do not save while the shop screen is open, because the Beta Seeds are in your inventory then, and autosaves count. Switch away from the Shock Bolt before any save, including a camp or zone autosave. Keep a backup of the co-op save.
• Kills made with coop devmenu's attack, gauge or enemy rows count toward Steam kill and skill achievements on the co-op save. A row's effect lasts until coop devmenu clear or the game exits.
• coop fly's climb, descent and dodges use the keys Z, S, Q and D, placed for an AZERTY keyboard. With coop slowmo on, holding R1 for a Burst skill slows time.
• A gift can be lost or doubled if the game stops (a crash, coop off or a Lua reload) between the remove and the mailbox write, if the friend leaves or her link stays down for over 60 s while the gift is on its way, or if you use the same item while t...

Stellar Blade Online 0.6.0-beta.3

Since 0.6.0-beta1

Changes since 0.6.0-beta1, the last version on Nexus (0.6.0-beta.2 went to GitHub only). The link protocol is still 13, so all 0.6.0 versions can play together.

• The Lion now plays its animations. Its three meshes hang their bones differently from the skeleton they share with the Behemoth (the Behemoth's update added a bone), so the engine refused to run the Lion's animation blueprint on them. The mod now runs it on a hidden Behemoth mesh. The Lion you see copies that pose bone by bone.
• The Lion no longer steps back before an attack that hits thin air. A lunging attack starts only when EVE stands past the point where its lunge stops. The three claw and dash chains now close in all the way.
• The Lion no longer runs into EVE and pushes against her for 2 to 3 s before it attacks. Its two plain claws, the only attacks that reach her at contact, recharge in 3 s instead of 6.
• Two of the Lion's slams now hit. The low jump (it rears up and slams both front paws down) and the high jump (the yellow attack you cannot parry) struck only through the front paws' collision and touched no one. Each now hits an area of 3.5 m around where the front paws land, as the game's own jump smashes do. A 5.3 m hop to the left during the high jump's wind-up, a wrong estimate in the mod's data, also took it off your line: it now only turns toward you.
• During a fight with the Lion, a frame of 50 ms or more came every second: a debug lookup of its animations, now removed.
• Near a camp, the phone booth scan froze the game for 60 to 79 ms every 4 s, in solo and in co-op. While linked, the cutscene check froze one frame every second. Both now ask the engine for the actors of a class, which takes a fraction of a millisecond, instead of walking through every object in memory. If your UE4SS cannot do that, they work as before.
• coop story [dump|find] lists the story and world state the running game holds (quests, mission records, zones, doors), read only. It is a test tool from the project's first outside contribution, by ghost86089-bot.

Known issues:

• EVE's finishers on the Lion can land 20 to 100 cm off. The Lion shows no hit flash and no death dissolve.
• With coop fly on, walking forward in the air on an AZERTY keyboard flies (Z). With coop slowmo on, holding R1 for a Burst skill slows time.

The Lion changes were tested in game, except the two slams. The booth and cutscene changes were not tested yet. Report problems on the Discord with coop-report.txt, coop-link.log and UE4SS.log.

0.6.0 (since 0.5.0)

Changes since 0.5.0. Both players need 0.6: the link protocol changed (13), so 0.5 and 0.6 cannot play together.

• Each player's .pak mods are named over the link. A notice says which ones your friend lacks.
• A friend's CNS outfit shows on their ghost when your own CNS packs declare its files.
• A notice warns when UE4SS-settings.ini has HookBeginPlay or bUseUObjectArrayCache on. HookBeginPlay can crash the game when EVE lets go of a movable crate.
• A guide opens at the first launch, in the game's 22 languages, with art of Mother Sphere by timediffer24. The Guide row of the co-op menu opens it again.
• coop lion spawns the Lion, a boss cut before release, as an enemy to fight on a co-op save. The mod adds 220 table rows written for it: its stats, 21 skills timed on its own animations and a second phase below 60 % HP. coop lion intro plays its 13 s entrance first. The rows stay in memory until the game closes. Only your game has the Lion.
• coop wear puts EVE in cut looks found in the game files: Nyaaa (mechanical cat ears), Mecha Rabbit ears, Gothic Rose, Daily Rider, Planet Diving Suit (5th) V2 and Golden Skin Suit. It changes the meshes drawn, not your equipment. Your friend sees it on your ghost.
• The viewer shows more cut models with its free camera: coop gardener and coop tendril (two Naytibas, with their animations), coop mann (an early Mann), coop nier (seven grey NieR machine shapes from the DLC files), coop orcal and coop enya (prototype statues).
• coop scene emil plays Emil's farewell from an ending of the first DLC, near Emil's spot in the Wasteland. coop scene orcal plays Orcal's monologue from the 2022 trailer, in his room in Xion. Both run on a co-op save through the game's own cutscene player.
• coop lines adam, warrior, quinn or skyhall shows the subtitles of a scene cut before it was voiced, in the chat's feed, timed as in the game files. It needs the co-op UI. The game has most of these lines in English and Korean only, so other languages show the Korean.
• coop fly on and coop slowmo on turn on the developer flight (hold R2, or Z on the keyboard, in the air after a jump) and slow motion (hold R1 on a controller) that the game ships switched off. Both need a co-op save. Slow motion waits while a friend is linked.
• Doro runs on all fours through EVE's dash instead of hopping. Its clips stay loaded and the drone is hidden during the look.
• The phone booth scan waits while EVE runs.

Stellar Blade Online 0.5.0-beta.1

Stellar Blade Online 0.5.0-beta.1 (the mod was called StellarCoop until now; its folder and files keep that name).

Both players need 0.5.0: it uses protocol 12, so a 0.4 game cannot link with it. Only the Leviathan viewer has run in game so far; everything else below is new and has not been tested between two PCs yet. Back up your saves.

New

• Shared quests (off by default): quest steps the host and the guest make together also count in the guest's co-op save.
• Kills count only for a player who took part in the fight: you hit the enemy, the game counts you as the last player on it, or you were within 30 m. An enemy or a boss your friend kills without you gives you nothing. This replaces kill_credit=all.
• Your friend can revive you by standing next to you for 3 s (off by default). With both players down, each respawns at a camp.
• The guest's game waits while the host watches a cutscene.
• In a shared area, only the host's camp rest brings the enemies back, and a notice says so.
• Solid partner (off by default): your EVE stops at your friend's.
• Night Operation's run: coop nightop sends five timed waves of the game's monsters, solo or, started by the host, for both players with a shared timer and score. Points buy items in a reward shop, on a co-op save only. coop challenge runs graded challenges on the same code. Parts of it adapt code from Survival Protocol by SchizoEffective, used with the author's permission.
• Doro races: record a track with checkpoints (F9), then race your friend with both EVEs drawn as Doro. The driving works like a car, with drift (R2 or B).
• The co-op line: F5 next to a camp phone booth opens a page to host, invite or join.
• The co-op menu and the co-op saves question work with an XInput controller and the mouse.
• Your friend's ponytail moves as cloth, as in solo (on by default).
• coop leviathan shows Leviathan, a Naytiba cut from the game, with a free camera for filming. It cannot be fought.
• status_overlay: a compact or detailed status line above the partner card. coop mark writes a numbered line in both players' logs.

Fixed

• About 40 problems found by a review of the whole code, among them an enemy killed by the guest alone that came back to life, and a crash when the other player sent a path starting with //.
• Following the host's fast travel stays off: the game's fast travel does not check that your save has activated the camp.

Update from 0.4
Close the game, copy coop-settings.txt out of Mods\StellarCoop, delete that folder, install the new one and put coop-settings.txt back. Your file's kill_credit=all becomes together.

StellarCoop v0.4.0-beta.1

Experimental beta. Both players need this version: it runs protocol 11, and a 0.3.x game cannot link with it.

Changes since 0.3.0-beta.1

• Enemies stand in the same place and attack the same way on both screens (same place, experimental, on by default). The game that owns an enemy runs its AI; the other game's copy follows it.
• An enemy attacks whoever hit it last, or the nearer player.
• The guest can execute common enemies.
• Both games have the same enemies where you play together (same spawns, experimental, on by default), with an option for up to 3 extra enemies each (enemy_extra, 0 by default).
• Shared boss fights (experimental, on by default): one HP bar, the phases and the summons in both games, and the arena and the intro for the guest too. Only the host's finisher ends a boss in its finish stance.
• Knockdowns and launches on shared enemies happen on both screens.
• Shared enemies get more HP and balance with two players (enemy_hp_scale 1.35 and enemy_balance_scale 1.15 by default, the host's values).
• kill_credit: kill rewards for every shared enemy, or only the ones your EVE hit.
• The co-op menu, notices, chat, partner HUD and co-op saves question follow the game's language, in the 23 languages the game ships.
• photo_pause=scenery keeps the world moving in photo mode (experimental).
• coop saves refresh <0-4> makes a new co-op copy of one of your saves, after a backup of the old one.
• A wider co-op menu, and clearer notices about the co-op saves.
• Fixed: with "Don't ask again", the co-op saves did not always switch on when the game started.
• Fixed: at game start, shared enemies could stay off when the co-op saves switched at the same moment.

Requirements

• Stellar Blade on Steam (PC), game build 24463856.
• UE4SS v3.0.1 Beta, as packaged in "Stellar Blade UE4SS 1.3".
• Windows, or Linux with Proton.
• Optional: ConsoleEnablerMod, from that UE4SS package, for the coop console commands.

Install

Close the game first. Unzip the file and copy the StellarCoop folder into SB/Binaries/Win64/ue4ss/Mods/. On the title screen, wait for the co-op saves question, then use Load Game. INSTALL.md in the zip has the full guide.

Tested and not tested

On 2026-10-21 two players played this version on the co-op saves with shared enemies and same place. Shared bosses, same spawns, extra enemies and executions by the guest have not been tested in game yet. Back up your saves first.

SHA-256 of StellarCoop-v0.4.0-beta.1.zip: 35c35a3ac40ed240e160bcc47117d008555f7a60257cc8308f555df40cf5a4d8

StellarCoop v0.3.0-beta.1

Experimental beta. Both players need this version: it runs protocol 9, and an older version cannot link with it. The player who tries to join sees a version-mismatch notice.

Changes since 0.2.0-beta.1

• F5 opens an in-game co-op menu, with Host a session as its first row. F6 and F8 work as before. A settings file from an earlier version has no menu_key line: the menu then opens on that file's host_key (F5, or the key you set there), and no key hosts at once. The menu is keyboard only.
• The menu's Options page changes the settings in game. Each change rewrites only that line of coop-settings.txt, with a coop-settings.old.txt backup. Keys can be rebound from the menu.
• Session chat: Enter opens a text box, 200 bytes per message. The last 50 lines stay in memory only and are cleared when the session ends. Chat text is never written to the logs.
• A partner card at the top left shows your friend's name, HP, shield and Beta, with their ping and map. A marker above their ghost shows their HP and shield, and turns into an arrow with the distance at the screen edge when they are out of view.
• Join codes. Options > Session > Who can join is Friends, With a code or Invited only. With a code, the menu shows a 7-character code to copy and send, and the other player types it under Join with a code. The host accepts or refuses each player who is not a Steam friend. No answer within 60 s counts as a refusal, and a refused or removed player cannot come back to that session.
• Shared enemies are on by default. They start by themselves once both players are linked, play a co-op save and are on the same map. Every common Naytiba is shared; bosses, Alpha Naytibas, the Gorgon and the two laser turrets are left out for now. Each pair shares HP, balance and death, and each copy still moves on its own. A notice says what is missing when sharing cannot start.
• Automatic co-op saves. At the title screen the mod asks whether to play on co-op copies of your saves (StellarBladeCoop00.sav to StellarBladeCoop04.sav). Your own save files are never written, and the mod backs them up to %LOCALAPPDATA%\SB\Saved\StellarCoopBackups\ before the first copy. Setting: auto_coop_save=ask, always or off.
• The ghost can get up to 60 poses a second (send_rate 10 to 60, default 60). Poses go out as changes against a full pose sent every 250 ms. In tests, 60 poses a second took 89 to 131 KiB/s, and the sender holds poses back above 192 KiB/s. An old settings file with send_rate=20 moves to 60 once.
• coop ui reset gives the game its keys back, and coop ui off hides the on-screen UI until the mod reloads.
• The menu, the chat, the partner HUD, the status line (F6) and the notices use French when the game is in French, and English otherwise. ui_language=english keeps them in English. The Steam link's notices and UE4SS.log stay in English.

v0.2.0-beta.1 had no GitHub release. Coming from v0.1.1, you also get synced photo mode: when one player enters photo mode (P), the other's game pauses about half a second later, until the photographer leaves photo mode (photo_sync=both on both PCs, the default). Since 0.2.0 the mod is under GPL-3.0-or-later.

Requirements

• Stellar Blade on Steam (PC), game build 24463856.
• UE4SS v3.0.1 Beta, as packaged in "Stellar Blade UE4SS 1.3".
• Windows, or Linux with Proton.
• Optional: ConsoleEnablerMod, from that UE4SS package, for the coop console commands. The keys work without it.
• Both players on this version and the same game build.

Install

Close the game first. Unzip StellarCoop-v0.3.0-beta.1.zip and copy the StellarCoop folder (the one that holds enabled.txt) into SB/Binaries/Win64/ue4ss/Mods/. Start the game. On the title screen, choose Decide later until your saves are backed up. Load a save and press F6. The screen shows Co-op: not in a session.

To update from an earlier version, copy coop-settings.txt out of the old Mods/StellarCoop folder if you changed a setting, delete that folder, install the new one and put the file back. A 0.2 settings file says shared_enemies=off, so shared enemies stay off until you turn them on in Options > Combat. A 0.1 settings file has no shared_enemies line, which counts as on.

INSTALL.md in the zip has the full guide: checking the files against SHA256SUMS.txt, Windows Defender (the DLL is not signed), save backups and Steam Cloud, the co-op saves, uninstalling, and which logs to send.

Not tested in game yet

The co-op menu has been seen working in game. Join codes, shared enemies, the automatic co-op saves, 60 poses a second, the chat, the partner HUD, synced photo mode and the optional looks have not been tested in game yet, and neither have longer sessions or level changes between two PCs. Back up your saves before you try them (INSTALL.md, "Saves and Steam Cloud").

SHA-256 of StellarCoop-v0.3.0-beta.1.zip: d9c6c94f7e0ad26cb9ebc11fcbc31b86d560ef6cff01e0447d8b5c16ac39e8b0

StellarCoop v0.1.1 (experimental)

Experimental. Fixes from the first test between two PCs. Both players need this same version.

Fixes

• The friend's ghost now appears. Under this UE4SS build, every ghost build in v0.1.0 failed with Ghost not built: ... has no instance inside lua_instances unordered map, solo or with a friend. The ghost is now built in steps without a Lua coroutine. A failed build is tried again 2 s later, up to 3 tries, then a notice shows on screen.
• The co-op no longer stops after a death, a fast travel or a load. On Windows, EVE being re-created could stop the native part for the rest of the run (engine off: fault 0xc0000005 at StellarCoop.dll+0x6015f). The old object is now detected as gone.
• The 60 s stream line in the log shows the real bytes sent instead of 0 bytes each.

Install

Close the game, then unzip StellarCoop-v0.1.1.zip into SB/Binaries/Win64/ue4ss/Mods/ and replace the old files. INSTALL.md in the zip has the full guide.

SHA-256 of StellarCoop-v0.1.1.zip: e493ab3e0eb438047e701b34f00cf7600c3ccda01f8be2577130540d7a731662

StellarCoop v0.1.0 (experimental)

Experimental. First public build of StellarCoop, a co-op mod for Stellar Blade (PC, Steam). It has not yet been tested
between two PCs: expect bugs, and back up your saves.

What it does

• Two Steam friends play together, each in their own world with their own save. Nothing is synced between saves
  (unlocks, outfits and equipment stay yours).
• You see your friend as a ghost EVE that moves like them in real time, in the outfit they wear. An outfit your game
  does not have (a DLC you do not own) shows as the base suit. The ghost only shows when you are on the same map.
• Connection through Steam's relays, no server; it works across countries.
• Invite with the Steam overlay (Shift+Tab) or F5 (host and invite), F6 (status), F8 (leave); keys can be changed
  in coop-settings.txt. Short notices show above EVE.
• Optional looks: cloth ponytail, outfit colours, attack effects (coop look cloth|dyes|effects on), off by default.
• Research previews (not a playable mode yet): the cut Night Operation mode (coop no, a probe) and its Xion recruiter
  (coop recruiter), both only on a dedicated co-op save slot (see INSTALL.md).

Install

1. Requirements: Stellar Blade on Steam (game build 24463856) and UE4SS "Stellar Blade UE4SS 1.3" with ConsoleEnablerMod on.
2. Close the game. Unzip StellarCoop-v0.1.0.zip into SB/Binaries/Win64/ue4ss/Mods/ so that you get
   Mods/StellarCoop/Scripts/main.lua and Mods/StellarCoop/StellarCoop.dll.
3. Start the game, load a save, open the console (F10 or ~) and type coop status. The answer goes to
   ue4ss/UE4SS.log (lines with [StellarCoop]).

Both players need this same version. INSTALL.md in the zip has the full guide: checking the files, Windows Defender
(the DLL is not signed), save backups and Steam Cloud, the co-op save slot, uninstalling, and which logs to send.

SHA-256 of StellarCoop-v0.1.0.zip: f89a29148bd392635bc34fc9f7dac5ee0ddb3bd1131a60b9d863f862b01dc837