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[Utility & Helpers](/categories/utility) 4. / 5. chemaclass/phel-connect4 ActiveProject[Utility & Helpers](/categories/utility) chemaclass/phel-connect4 ======================== Two-player terminal Connect 4 in Phel, with an optional bitboard minimax AI. 10 Since Apr 18Pushed 1mo agoCompare [ Source](https://github.com/Chemaclass/phel-connect4)[ Packagist](https://packagist.org/packages/chemaclass/phel-connect4)[ RSS](/packages/chemaclass-phel-connect4/feed)WikiDiscussions main Synced 1w ago READMEChangelogDependenciesVersions (1)Used By (0) Connect 4 in Phel ================= [](#connect-4-in-phel) Two-player terminal [Connect 4](https://en.wikipedia.org/wiki/Connect_Four) written in [Phel](https://phel-lang.org), a Lisp that compiles to PHP. Optional minimax AI opponent. ``` 1 2 3 4 5 6 7 |. . . . . . .| |. . . . . . .| |. . . . . . .| |. . . . . . .| |. . . O O O .| |. . . X X X X| Red (X) wins! ``` Install ------- [](#install) Requires PHP 8.3+ and Composer. ``` composer install ``` Run --- [](#run) Use the composer scripts: ``` composer play # two players (default) composer play:2p # same as above, explicit composer play:1p # vs AI; you play Red (move first), AI plays Yellow composer play:ai-first # vs AI; AI plays Red (moves first), you play Yellow ``` Or run directly with env vars: ``` ./vendor/bin/phel run src/phel/main.phel # 2 players AI=yellow ./vendor/bin/phel run src/phel/main.phel # AI = yellow AI=red AI_DEPTH=6 ./vendor/bin/phel run src/phel/main.phel # AI first, deeper search ``` How to play ----------- [](#how-to-play) - Red (`X`) moves first, then players alternate. - Drop a token into any column that is not full; it falls to the lowest empty row. - First player to line up **four in a row** (horizontal, vertical, or diagonal) wins. - Board full with no winner → draw. ### Commands at the prompt [](#commands-at-the-prompt) InputAction`1`..`7`Drop token into that column`u`Undo the last move (replays history from scratch)`q` or `quit`Abort gameConfiguration ------------- [](#configuration) Environment variables: VariableDefaultMeaning`AI`*(off)*`red` or `yellow` — which side the AI plays`AI_DEPTH``5`Minimax search depth. Higher = stronger and slower (`5` ≈ 2–7s, `6` ≈ 10s, `7` ≈ 35s per move)`COLOR`*(on)*Set to `0` to disable ANSI colors and screen clearingExample: strong AI, no colors, piped input. ``` COLOR=0 AI=yellow AI_DEPTH=4 ./vendor/bin/phel run src/phel/main.phel ``` Tests ----- [](#tests) ``` ./vendor/bin/phel test ``` Covers board logic, game state transitions, and AI tactics (forced win, forced block, center preference). Project layout -------------- [](#project-layout) ``` src/phel/ board.phel ; pure board ops: make/drop/winner?/valid-cols game.phel ; TGame struct: step, undo, game-over? render.phel ; ANSI rendering + display names ai.phel ; negamax with alpha-beta pruning main.phel ; CLI loop tests/phel/ board_test.phel game_test.phel ai_test.phel ``` AI notes -------- [](#ai-notes) - **Bitboard representation**: two 49-bit ints encode the position (columns laid out as 7 bits each, with a separator bit to make shift-based win detection safe). - **Win detection**: for each axis shift (vertical 1, horizontal 7, diagonal 6, diagonal 8), `pos & (pos >> s) & m & (m >> 2s)` detects a 4-in-a-row in a handful of bitwise ops instead of scanning 69 windows. - **Negamax + alpha-beta**: center-out move ordering so good candidates prune the wide branches early. - **Heuristic**: per-axis 2-in-a-row and 3-in-a-row counts via `popcount`, plus a center-column bonus. - **Depth-aware scoring**: terminal wins return `win-score + depth`, so the AI prefers winning faster and losing later. - **Opening shortcut**: the first move (empty board) plays the center column without searching. During the AI's turn you'll see a `thinking...` line while the search runs; when it returns, the move and elapsed time are printed before the next board render. Every turn also shows a `Last: → column N` line so you can see what just happened after the screen clears. ### Health Score 20 — LowBetter than 13% of packages Maintenance59 Moderate activity, may be stable Popularity2 Limited adoption so far Community6 Small or concentrated contributor base Maturity11 Early-stage or recently created project Bus Factor1 Top contributor holds 100% of commits — single point of failure How is this calculated?**Maintenance (25%)** — Last commit recency, latest release date, and issue-to-star ratio. Uses a 2-year decay window. **Popularity (30%)** — Total and monthly downloads, GitHub stars, and forks. Logarithmic scaling prevents top-heavy scores. **Community (15%)** — Contributors, dependents, forks, watchers, and maintainers. Measures real ecosystem engagement. **Maturity (30%)** — Project age, version count, PHP version support, and release stability. ### Community Maintainers ![](https://www.gravatar.com/avatar/3d166420c6770c5941e10bd68b2d26501eabb432e280d8e6eba0a344bcc1e5ae?d=identicon)[Chemaclass](/maintainers/Chemaclass) --- Top Contributors [![Chemaclass](https://avatars.githubusercontent.com/u/5256287?v=4)](https://github.com/Chemaclass "Chemaclass (16 commits)") --- Tags lispphel-langphp ### Embed Badge ![Health badge](/badges/chemaclass-phel-connect4/health.svg) ``` [![Health](https://phpackages.com/badges/chemaclass-phel-connect4/health.svg)](https://phpackages.com/packages/chemaclass-phel-connect4) ``` ### Alternatives [shrink0r/monatic Fiddling with the monad concept in php 245.3k2](/packages/shrink0r-monatic) PHPackages © 2026 [Directory](/)[Categories](/categories)[Trending](/trending)[Changelog](/changelog)[Analyze](/analyze)