Coliseum v4.0.2

Fixed

• Engines that take a while to load no longer fail with "Engine startup timeout". Some engines load a large network before they answer, which can take more than 10 seconds on some PCs. Coliseum now gives an engine 30 seconds to start, and its first check of which protocol an engine speaks waits up to 20 seconds for an engine that is still loading.
• Clearer start-up errors. When an engine doesn't start, the message now names it, says what it didn't answer and quotes the last thing it printed. For example: "Engine startup timeout: Absurd-1.0.exe did not answer "uci" within 30 s (it printed nothing)". Before, it only said "Engine startup timeout (uciok/readyok)" without saying which engine.
• The right engine gets moved. If one engine was slow, 4.0.1 could also run its opponent from its own folder ("did not start as a copy") even though that opponent had started fine. Only an engine that didn't answer is affected now

Coliseum v4.0.1

Fixed

• Commercial engines that wouldn't start (Houdini 6, Deep Shredder 13 and similar) now work again. Engines added by path run as a copy, so you can rebuild an engine while Coliseum plays with it. Some commercial engines check their licence against the location of their own .exe, so the copy sat there silently until "Engine startup timeout (uciok/readyok)".
  • Coliseum now notices: when the copy doesn't answer but the original does, it runs that engine from its own folder from then on.
  • It switches over without you doing anything. The game that hit the problem is started again, and a note appears in the game log.
  • If you later relink the engine or put a new build in its place, Coliseum tries the copy again.
• Wrong arrow on the Analysis Board with some engines (reported with AggroChess). An engine that was slow to answer "stop" kept printing lines about the previous position after you moved on, and Coliseum drew them on the new one: an arrow from an empty square, the old evaluation. Those lines are now ignored until the engine has finished with the old position.
• Faster engine checks: when Coliseum asks a new engine which protocol it speaks, it now waits for that test run to close before starting the engine for real. Engines that only allow one copy of themselves to run, or that lock files next to them, no longer collide with their own test run

Coliseum v4.0.0

Coliseum can now tell you how aggressively your engines win. Version 4 builds in the Engine Aggressiveness Statistics (EAS) Tool V6.0 by Stefan Pohl (www.sp-cc.de).

New: the Aggressiveness tab

• The EAS score: wins with sacrifices count for more (bigger and earlier sacrifices most of all), and so do short wins and few "bad draws". It's worked out from each engine's own wins, so a weaker engine can still score high.
• Any games: score the last tournament, any PGN file or your Quick Match archive.
• Two ways to score: Main engine only (the tool's gauntlet version, for testing one engine against a field) or Every engine.
• Clear results: each engine's score split into sacrifices, early sacrifices, short wins and bad draws, with sacrifices broken down by size (queen, 5+ pawns, down to 1 pawn). A warning shows when there are too few games for a reliable score.
• Interesting wins: the games the tool picks out open straight in Game Review, or save them as a PGN.
• Reports are kept: every run is saved, so you can compare engines and versions later. The tool's full report is always there next to Coliseum's summary.

New: EAS after a tournament

A finished or stopped tournament has a Run EAS button on its results page. The scores appear right there, with a link to the full report.

Good to know

• Windows only: the EAS tool is a set of Windows scripts. On Linux, the Aggressiveness tab explains that it needs Windows; everything else works as before.
• Same conditions: scores depend on the time control, openings, opponents and whether games are played to mate, so compare engines run under the same conditions.
• Unusual names: engine names with characters that break batch scripts (like &, ( or %) are handled for you.

Credits

EAS Tool V6.0 by Stefan Pohl (www.sp-cc.de). It uses pgn-extract by David J. Barnes and PGN tools by Norman Pollock. The tool is included unchanged; Coliseum runs it exactly as you would and reads its report.

Coliseum v3.9.0 “Trial by Combat”

Coliseum v3.9.0

Coliseum is now a proper engine-testing tool: SPRT tests, adjudication, fixed depth and node limits, opening suites from EPD and PGN files, WinBoard engines, and a Linux version. It also has a new look, an opening book manager, and a sidebar you can arrange yourself.

New look: the Coliseum theme

• Roman colours: Coliseum now looks like its namesake, with warm travertine stone, bronze and dark stone. The original neon green is still there as the Matrix theme.
• Easier to read: the new default board is light and dark stone with classic white and black pieces, which are told apart by brightness rather than red and green, so they're easy to read if you're colour-blind.
• Your choice: in Settings, pick a theme, one of five boards (Travertine, Marble, Wood, Slate blue, Matrix) and a piece set (Classic, Ivory & bronze, Matrix red). The preview updates as you choose.

New: opening book manager

• Where: Local Engines is now Engines & Books, with a tab for your Polyglot opening books.
• At a glance: each book shows its size, how many positions it has and its favourite first moves.
• Manage them: add books with a button (or by dropping a .bin file), open the books folder, or delete a book you don't need.
• Explore a book: click any book to walk through it move by move on a board, with how often the book plays each move.

New: customise the sidebar

• Your order: click Customize at the bottom of the tab list and drag the tabs into the order you like.
• Hide tabs: hide the ones you don't use with the eye button; Reset brings the original layout back.

Smaller changes

• Installer name: the Windows installer is now built as Coliseum-Setup-<version>.exe, which matches the update file without renaming.

New: SPRT testing

Find out whether a new build of your engine is really stronger, the way Fishtest and OpenBench do it.

• New format: pick SPRT Test in the tournament lobby, choose the new engine and the base engine, and Coliseum plays game pairs (same opening, colours swapped) until the test decides.
• Your bounds: set Elo0, Elo1, alpha and beta, or use a preset: gain [0, 5], big gain [0, 10] or no regression [-5, 0]. A game limit stops tests that never decide.
• Live results: the log-likelihood ratio between its two bounds, the Elo difference with a 95% range, the likelihood of superiority, W/D/L and the game-pair counts (pentanomial).
• Clear verdict: "H1 accepted" means the new engine is stronger; "H0 accepted" means it isn't. Games still running when the test decides are stopped and not counted.

New: adjudication

Games that are already decided no longer have to be played out to mate.

• Resign: both engines agree one side is losing by at least a set score for a set number of moves.
• Draw: after a set move, both engines' scores stay close to 0 for a set number of moves.
• Move limit: a game that runs past a set length is a draw.
• Where: adjudication works in tournaments, SPRT tests and Elo estimation, and is marked as "adjudication" in the PGN.

New: search limits

Besides a clock, games can now use a fixed time per move, a fixed search depth or a fixed number of nodes. Fixed nodes make results independent of how busy your PC is.

New: opening suites from EPD and PGN files

• Any suite: use EPD position files or PGN files (like the 8-move or UHO suites), in tournaments, SPRT tests and Elo estimation.
• Pairs: each opening is played twice, once with each engine as White.
• Options: play them in file order or shuffled, and choose how many moves of each PGN line to play.
• Checked first: Coliseum counts the openings when you pick the file, so a broken file shows up before the start.

New: WinBoard engines

• Detected automatically: Coliseum now supports WinBoard (xboard / CECP) engines as well as UCI. It asks each engine which protocol it speaks, and you can also set the protocol by hand in the engine's settings.
• Options: WinBoard engines' own options show up in Configure, like UCI options do.
• What works: WinBoard engines play in tournaments, SPRT tests, Elo estimation, Quick Match and Play. Analysis, Game Review and the Tactics Trainer still need a UCI engine.

New: Linux version

• Downloads: Coliseum now runs on Linux too, as an AppImage or a .deb package. AggroChess and Stockfish 17.1 come with it.
• Your files: engines and books you add on Linux are kept in ~/.config/coliseum.
• Updates: the Linux version updates itself from GitHub, just like the Windows one.

Coliseum v3.7.1 ‘Linked Engines

Coliseum v3.7.1

New: link engines by path

You can now use an engine from wherever it lives, for example your own build folder, without copying it into Coliseum's engines folder.

• Add engine by path: a new button in Local Engines. Pick one or more engine files and they appear in every engine list, marked Linked.
• Drag and drop asks first: when you drop an engine (or a folder of engines) on the window, Coliseum asks whether to Link it where it is or Copy it into the engines folder, like before.
• Rebuild any time: Coliseum runs a private copy of a linked engine, never the file itself, so Windows won't lock your .exe and your compiler can overwrite it while Coliseum is open. The next game picks up your newest build automatically.
• Tournaments stay fair: a tournament or Elo estimation run keeps the build it started with for every game, even if you rebuild halfway through. Resuming a tournament later continues with that same build.
• Nets and books still work: a linked engine runs with its own folder as its working directory, so files next to it (NNUE nets, configs) are found as usual.
• Moved or deleted files: a linked engine whose file is gone shows Not found, with Relink (point it at the new location and keep its rating, history and saved options) and Remove.
• Unlink is safe: removing a linked engine only removes the link. The file itself is never deleted.

Coliseum v3.7.0 “Play & Train”

Coliseum v3.7.0

Coliseum is now easier to use if you just want to play or train, not only test engines.

New: Play tab

Play against AggroChess in two clicks. AggroChess comes with Coliseum and plays aggressive, sacrificial chess in the spirit of Mikhail Tal.

• Quick setup: choose White, Black or Random, and a time control from bullet to classical (or no clock).
• Custom positions: paste a FEN to start from any position.
• Any engine: switch to any other installed engine if you want a different opponent.
• Clean board: no engine arrows or evaluation bar while you play, so nothing gives the engine's plans away.
• Review: when the game ends, open it straight in Game Review.

New: puzzles from your own games

The Tactics Trainer can now build puzzles from your Chess.com or Lichess games.

• No login: type your username, choose your last 25, 50 or 100 games, and Coliseum fetches them from the site's public archive.
• Your moves only: puzzles come from positions where you were to move: wins you missed, blunders you didn't punish, and mates you didn't find.
• Your words: puzzle descriptions say what you played, and a link opens the original game online.
• Standard chess only: Chess960 and other variants are skipped.

Tactics Trainer, reorganised

• Three sources: pick where puzzles come from (Engine Tournaments, My Games or a PGN File) at the top of the generator.
• Past tournaments: finished and stopped tournaments are now kept automatically, so you can turn any of them into puzzles without exporting files. Tournaments played before 3.7 can still be loaded as PGN files.
• Library filter: show all puzzles, only engine-game puzzles, or only puzzles from your own games.
• Better default: Stockfish is picked as the analysis engine when it's installed.

Estimated Elo in Game Review

Game Review now shows an estimated Elo for each player, worked out from how accurately they played, with a ± range that is wider for short games. It's a rough guide from a single game, not a rating.

Fixes

• Frozen clocks: in rare cases an engine that ran over its time could freeze its clock, show ∞, and never lose on time, stalling a tournament. Fixed.
• Narrow windows: the Tactics Trainer's results could be pushed off-screen on smaller windows. Fixed.
• Portrait windows: live tournament boards now stack instead of shrinking the other games to tiny boards.
• Game Review header: the result badge is no longer squashed by long player names.
• Wording: "1 games at once" now reads "1 game at once".
• Proxies: online features follow your system's proxy settings.

Coliseum v3.6.0

Coliseum v3.6.0

A big update to tournaments, ratings and the layout.

New: Gauntlet tournaments

One main engine plays every opponent as many times as you choose. It's ideal for testing a new version of your engine against a field. You get its score, its Elo difference against each opponent with an error margin, and a performance rating.

Fairer tournaments

• Matches: every match is now two games from the same opening, one with each engine as White, so no engine gets the luckier colour or opening.
• Openings: start games from a built-in set of 50 balanced openings, your own Polyglot opening book, or the normal starting position.
• New format: Round Robin is now available.
• Swiss: the rounds setting now works, and ties are split by Buchholz, then Sonneborn-Berger.
• Knockouts: a drawn match no longer goes to White. A level match gets up to two more 2-game tiebreaks, then sudden-death games.

Several games at once

Run more than one game at the same time. Coliseum suggests a safe number for your CPU, and you can watch every game live and click any one to follow it on the big board.

Elo Estimation, redesigned

• Ratings: each engine's rating comes from every game it has played, with a ± range that narrows as more games come in.
• Easier to read: a leaderboard with confidence labels and a chart of how ratings changed over the session.
• Rating anchor: optionally fix one engine's rating, and the others are measured against it.
• Stopping: games cut short are no longer counted as draws.

Fixes and improvements

• Engine names: the real names reported by the engines now show on every board.
• PGN export: files now have full headers (event, round, players, ratings, time control, how the game ended).
• Time losses: engines are no longer flagged for being a few milliseconds over.
• Crashes: a crashed engine now loses the game instead of freezing the tournament.
• Resuming: leaving the Tournament tab mid-game no longer loses the live boards, and stopped tournaments can be resumed from the lobby.

New layout

The whole app has been reworked so it no longer gets squished on smaller windows. The sidebar collapses on narrow screens, and the boards in Quick Match, Game Analysis and Board Editor resize to fit.

Before you update

• An unfinished tournament saved by v3.5 can't be resumed in v3.6. You'll be offered the option to discard it.
• Engine ratings are recalculated from game history, so they may shift a little the first time you open v3.6.

Coliseum Developer Log - v3.5.0

What’s New in v3.5.0

Game Review Overhaul

• Rebuilt move classification around win probability instead of raw centipawns: Brilliant, Great, Best, Excellent, Good, Book, Forced, Inaccuracy, Mistake, Miss and Blunder.
• Accuracy now uses the Lichess formula, and ACPL is shown alongside it.
• Book moves are detected from the opening books in your books folder.
• Added a clickable evaluation graph, a Key Moments list, and a best-move arrow with the engine’s preferred line for every weak move.
• Fixed Brilliant moves never being awarded, and 1.2–1.8 pawn errors being labelled “Interesting”.
• Fixed evaluations dropping to 0.00 when an engine’s last output line had no score.

Live Analysis

• Shows the top 3 engine lines in standard notation.
• Fixed stale evaluations and arrows from the previous position showing up after a move.
• Fixed the eval bar using the wrong side to move when stepping back through a game.

Puzzle Generator

• New puzzle types: Punish the Blunder, Missed Tactics, and forced mates confirmed to end in checkmate.
• Every solver move is checked to be the only winning move, so each puzzle has one clear answer.
• Removed duplicate puzzles from the same mating attack or tactic.
• Added theme tags (fork, sacrifice, back-rank mate, smothered mate, discovered attack…) and difficulty ratings.

Tactics Trainer

• The opponent’s blunder is played on the board before you solve.
• Added hints, solved/failed tracking, success rate and streaks, plus a “Next Puzzle” button that jumps to unsolved puzzles.
• Alternative mates that are just as fast are accepted, and other winning alternatives are checked by the engine.
• New filters for unsolved and failed puzzles and for themes, plus sorting by difficulty.
• Fixed a freeze when checking alternative mates.

Fixes

• The Game Analysis layout now fits smaller windows.
• Analysis engines are shut down cleanly when the app closes.

Coliseum Developer Log - v3.4.0

What's New in v3.4.0

Swiss System Improvements

• Integrated career ELO stats from the engine store so tournaments are seeded by engine strength.
• Implemented robust BYE auto-resolution to instantly skip non-playing matches.

Double Elimination Tournaments

• Fully automated Winners Bracket, Losers Bracket, and Grand Finals progression.
• Added support for a Grand Finals Reset match (with automatic color flipping) if the Losers Bracket Champion wins the first match.
• Cleaned up standings and scoreboard UI to hide the BYE engine indicator.

Coliseum Developer Log: Version 3.3.0 (Board Editor)

This release introduces the highly requested Board Editor tab, giving users full creative control over custom chess setups.

Brand New Board Editor

• Piece Palette & Stamp Placement: Features white and black piece palettes. Place pieces on the board by dragging them or click a piece to "stamp" multiple copies quickly.
• Eraser Tool: A new utility to quickly wipe individual pieces off the board.
• State Controls: Fine-tune position properties, including active turn color, castling rights (K, Q, k, q), and en passant double-push targets.

FEN Operations & Analysis Hand-off

• FEN Copy/Paste Loader: Paste any valid FEN string to load positions instantly, or copy the active board's FEN with a one-click clipboard action.
• Direct Analysis Link: Click "Load into Game Analysis" to automatically redirect to the analysis panel with your custom layout loaded and ready for engine evaluation.
• Quick Tools: Reset to standard start, clear the board completely, or flip the board view orientation.