CE Games

A collection of games for the TI-84 Plus CE, built with the CE C/C++ Toolchain.

Games

Game	Description	Demo
Chess	chess GUI & engine with opening book, 3 difficulty levels
Pong	Pong vs AI with 5 levels, and an "infinite" level
Sudoku	Easy, medium and hard mode with timer, pencil and more

Prerequisites

• CE C/C++ Toolchain v12+ installed to ~/CEdev
• CEDEV and toolchain bins on your PATH:

  export CEDEV="$HOME/CEdev"
  export PATH="$CEDEV/bin:$PATH"

Building

Build all games:

make

Build a single game:

make pong

Clean all build artifacts:

make clean

Rebuild from scratch:

make clean && make

Testing with the emulator

Using hunterchen7/ti84ce:

# Send a single program
cargo run --release --example debug -- sendfile ../games/pong/bin/PONG.8xp

# Bake all games + libs into a ROM
cargo run --release --example debug -- bakerom games.rom ../games/*/bin/*.8xp ../games/libs/*.8xv

Project structure

ce-games/
  Makefile        # Top-level build (builds all games)
  shared/         # Common utilities (input, rendering helpers)
  libs/           # CE C library .8xv files
  pong/
    Makefile      # Game-specific build config
    icon.png      # 16x16 program icon
    src/main.c    # Game source
    bin/          # Build output (.8xp) — gitignored
    obj/          # Build intermediates — gitignored

Each game is a standalone CE C project with its own Makefile that includes the toolchain via cedev-config --makefile.

Chess

A chess engine written in C for the TI-84 Plus CE's eZ80 processor (48 MHz, 256 KB RAM). Plays a full game of chess with an opening book, animated piece movement, and legal move highlighting.

Estimated Elo Ratings

Platform	Time/Move	Estimated Elo	Method
eZ80 (48 MHz)	2s	~1355	50 games vs SF-1320
eZ80 (48 MHz)	5s	~1700	Node-limited vs Stockfish
eZ80 (48 MHz)	10s	~1800	Node-limited vs Stockfish
eZ80 (48 MHz)	15s	~1950	Node-limited vs Stockfish
eZ80 (48 MHz)	30s	~2100	Node-limited vs Stockfish
Desktop (M5 MBP)	0.01s	~2583	100 games vs Stockfish
Desktop (M5 MBP)	0.1s	~2700	189 games vs Stockfish

Ratings are estimated by playing against Stockfish's UCI_LimitStrength mode (single-threaded) at various UCI Elo levels. On-calculator ratings use node-limited search to simulate the eZ80's throughput (~330-400 NPS at 48 MHz). Desktop ratings are from direct time-controlled matches. Full results in chess/bench/RESULTS.md.

Engine Features

Search:

• Alpha-beta negamax with iterative deepening
• Principal variation search (PVS) with aspiration windows
• Null move pruning (R=2)
• Late move reductions (LMR)
• Futility pruning (depth <= 2)
• Quiescence search with delta pruning
• Check extensions (up to 2 per path)
• Transposition table (4096 entries, always-replace)

Move Ordering:

• TT best move, MVV-LVA for captures, killer heuristic (2 per ply), history heuristic
• Staged generation (captures first, then quiets)

Evaluation:

• Texel-tuned piece-square tables (PeSTO-based) with tapered middlegame/endgame scoring
• Pawn structure: doubled, isolated, connected, and passed pawn evaluation
• Piece mobility (knight, bishop) with pawn attack awareness
• Bishop pair bonus, rook on open/semi-open files, king pawn shield
• Incremental material + PST updates in make/unmake

Opening Book:

• Polyglot format split across multiple AppVars (TI-OS file size limit workaround)
• 5 tiers (Small to XXL), up to 131K entries
• Probed from Flash with zero RAM cost

Difficulty & Move Variance:

• Easy mode uses move_variance to randomly select among root moves within N centipawns of the best
• Wider PVS window at root ensures accurate candidate scoring without picking blunders
• variance=5 gives natural-looking move variety with no measurable Elo loss
• Higher variance values (10-15) trade more Elo for greater unpredictability

Board Representation:

• 0x88 board with piece lists and incremental Zobrist hashing
• 32-bit hash + 16-bit lock for TT collision detection

UI

• 60 FPS double-buffered rendering (320x240, 8-bit palette)
• Animated piece movement with smooth interpolation
• Legal move indicators (dots for quiet moves, corner marks for captures)
• Last move highlighting, check indicator
• Board flips when playing Black
• 4 difficulty levels: Easy (2s), Medium (5s), Hard (10s), Expert (15s)
• Play as White, Black, or Random

Controls

Action	Key
Move cursor	Arrow keys
Select / confirm	Enter or 2nd
Deselect	Clear
Resign	Mode

Building

The chess game requires the opening book AppVars alongside the main program:

make chess

This produces chess/bin/CHESS.8xp and the book AppVars in chess/books/. Transfer both the .8xp and the book .8xv files to your calculator.

Controls

Pong

Menu / Level Select:

Action	Key
Navigate	↑ / ↓
Select	Enter or 2nd
Quit / Back	Clear

Gameplay:

Action	Key
Move paddle up	↑
Move paddle down	↓
Return to menu	Clear
Skip transition	Enter or 2nd

You control the right paddle. The left paddle is AI-controlled. You have 3 lives — lose one each time the AI scores. Lose all lives and it's game over.

Game Modes:

• Play — Campaign through 5 levels of increasing difficulty. Score enough points to advance.
• Infinite — Endless mode that gets harder every point you score. Color theme cycles every 5 points. How far can you get?
• Level Select — Jump to any level directly.