Netplay

Netplay

Netplay lets two players sync a single emulator session across devices using Argosy's rollback netcode. Sessions are one host + one guest (2 players total).

Netplay currently works only with the Built-in Emulator and a limited set of cores.

Supported cores

Core	Platforms
FCEUmm	NES / Famicom, Famicom Disk System
Nestopia	NES / Famicom, Famicom Disk System
Snes9x	SNES / Super Famicom
Genesis Plus GX	Genesis / Mega Drive, Master System, Game Gear, Sega CD, 32X
PicoDrive	Genesis / Mega Drive, Master System, Game Gear, Sega CD, 32X
Stella	Atari 2600
Beetle PCE	TurboGrafx-16 / PC Engine
FBNeo	Arcade, Neo Geo, CPS1 / CPS2 / CPS3

Link Cable multiplayer (Game Boy / GBC / GBA cable games, WonderSwan, Neo Geo Pocket) is not supported — those use a different synchronization model than Argosy's rollback netcode.

Core versions must match on both sides. Different Argosy app versions may still work but are not tested for compatibility.

Hosting a session

Start the game on your device via the built-in emulator, open the in-game menu, and choose Open Netplay Server. You pick a session mode:

• Open to Friends — any friend can join automatically.
• Private — friends can request to join; you see the request with their username and Accept or Decline.
• Invite Friend... — pick a specific online friend to invite directly.

Once the session is open, you keep playing. When a guest joins, they appear in the netplay HUD (see In-session HUD).

Joining a session

When a friend invites you, Argosy shows an invite modal: "[Friend] invited you to play [Game]" with Dismiss or Join buttons. Tap Join and Argosy walks through:

1. Matching core — fetches the required core. If you don't have it installed, it downloads automatically.
2. Verifying game — checks whether your copy of the ROM matches the host's (hash comparison).
   • If your ROM matches, it's used directly.
   • If you have the game but a different variant (region or version), a picker lets you choose which copy to use.
   • If you don't have the game at all, Argosy can download it from RomM before launching.
3. Joining session — connects to the host.

The join modal shows progress through each step. If a step fails (core unsupported, no matching ROM, connection rejected), the modal surfaces the error.

In-session HUD

A HUD in the top-left corner of the emulator shows:

• Game title
• Session mode (Open / Private / Invite Only) and player count
• Ping, color-coded:

Color	Ping
Green	Under 80 ms
Yellow	80–150 ms
Orange	150–200 ms
Red	200–300 ms
Dark red	300 ms+

• Host and guest names with P1 / P2 labels and avatar dots.

If the initial connection quality measures poor, Argosy shows a warning before starting the game: "Connection quality is [rating] ([N]ms ping, [N]ms jitter). Gameplay may be choppy." You can Continue Anyway or Cancel.

Single-player games and controller sharing

Netplay works on single-player games. Today both players share the same controller — the input for Player 1 is whatever the active side sends, so sessions work best for turn-based or side-by-side play where only one player is actively driving.

A future release will add controller swapping so two players can take turns holding the input on a 1-player game without restarting.

In-session restrictions

Action	Host	Guest
Quick Save / numbered save states	Allowed	Blocked
Quick Load	Blocked	Blocked
Rewind	Blocked (silent)	Blocked (silent)
Fast Forward	Blocked (silent)	Blocked (silent)
Cheats	Auto-disabled at session start	Auto-disabled at session start

Cheats are turned off automatically when a session starts; they return to their previous state after disconnecting.

Disconnects

• Peer drops mid-session — Argosy shows "Friend lost connection. Keep session open or close and exit?" Choose to keep waiting or close.
• Server drops — session resets to idle; connect to the server again to host or join.
• You suspend the device (lock screen, switch apps) — Argosy ends the session automatically. Guests leave, hosts close the session entirely. Your single-player game state stays loaded so you can resume on your own.

Requirements

• Both devices must reach the Argosy netplay server. If the server is unreachable, you cannot host or join.
• Both devices need a compatible core installed (Argosy auto-downloads missing cores on join).
• A RomM-synced library makes "join without having the ROM" workable; guests without RomM cannot download missing games during join.