Overboard! (PushFight iOS)

Overboard! is a native iOS app for playing the abstract board game popularized as Push Fight with friends, built with SwiftUI and Game Center turn-based matches — no backend.

Features

• Pass & Play — full local game on one device, with placement, move/push highlighting, undo, and animated pieces.
• Play Computer — four difficulty levels (Deckhand → Captain) against a built-in AI, fully offline. The level design (depth-limited imperfect play, random choice among near-equal moves) follows Maks Verver's Push Fight solver project; the solver's exact database is far too large to ship, so deeper levels use a heuristic alpha-beta turn search instead of perfect lookups.
• Play a Friend — Game Center turn-based match via the system invite UI.
• Ranked Lobby — auto-match against strangers from a single global queue, and ratings update after each ranked game.
• Match History — every finished game is stored locally and can be replayed move by move (scrubber + autoplay).
• Elo — standard Elo (K=32), starting at 1200, persisted locally and mirrored to a Game Center leaderboard (pushfight.elo).

Architecture

PushFightiOS/
├── PushFightCore/          Pure Swift rules engine (SPM package, no dependencies)
│   ├── GameState           Board, placement, BFS moves, pushes, rails, anchor, win detection
│   ├── GameRecord          Action log; replay/undo/scrub derive any state
│   ├── ComputerPlayer      Bitboard turn search + difficulty levels for Play Computer
│   └── Elo                 Rating math
├── App/
│   ├── Models/             GameSession (interaction/selection), stores (history, Elo)
│   ├── GameCenter/         GameCenterManager (auth, matchmaking, turn sync), matchmaker UI
│   └── Views/              Home, Game (board + HUD), History, Replay
└── UITests/                Smoke test playing a real game (placement → move → undo → push)

GKTurnBasedMatch.matchData carries a JSON OnlineMatchPayload { game: GameRecord, ranked, ratings } — the action log is the game, so sync, replay, and history all share one representation.

Development

Generate the Xcode project (requires XcodeGen) and run tests:

xcodegen generate
open PushFight.xcodeproj

cd PushFightCore && swift test          # engine tests
xcodebuild test -project PushFight.xcodeproj -scheme PushFight \
  -destination 'platform=iOS Simulator,name=iPhone 16 Pro'     # UI smoke test

If swift test fails with a manifest/linker error, the active toolchain is Command Line Tools; prefix commands with DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer (or run sudo xcode-select -s /Applications/Xcode.app).

Game Center

Online play requires an app record with the Game Center capability and a leaderboard whose ID matches EloStore.leaderboardID. To play online in the simulator/device, sign into Game Center in Settings (sandbox account while in development). Local pass-and-play works with no setup.

The board

4×8 grid, 26 tiles (a1, g1, h1, a4, b4, h4 are missing). Rails run along the top of row 4 and the bottom of row 1; every other outside edge is open — a piece pushed past an open edge falls off and loses the game for its owner.

      abcdefgh
    4   ▢▢▢▢▢    4    ▔ rail
    3 ▢▢▢▢▢▢▢▢ 3
    2 ▢▢▢▢▢▢▢▢ 2
    1  ▢▢▢▢▢    1    ▁ rail
      abcdefgh

Each player has 3 squares (move + push) and 2 rounds (move only). A turn is up to 2 moves followed by a mandatory push; the anchor sits on the last pusher and cannot be pushed. Lose by having a piece pushed off — or by being unable to push.