War Element — Alpha Build

A playable vertical slice of the War Element TCG: draw → resource → turn-based prep → speed-queue battle → win by elimination or slot capture. One local human (P1, bottom) vs. a rule-based AI (P2, top).

Run it

npm install
npm run dev      # → http://localhost:5173 (or --port N)
npm test         # 86 engine unit tests, headless (Vitest, no React)
npm run build    # tsc --noEmit + vite production build

How to play

• Deck select: on launch (and after each match) pick your deck and the AI's from Leaf/Pyro, Bore/Dusk, or Aqua/Dawn, then Start Match.
• Mulligan: click opening-hand cards to send back, confirm, redraw.
• Prep: glowing hand cards are affordable — click one, then a glowing Home slot to summon (any number per turn). Click a board card, then a glowing slot to move (one move per priority turn). Pass Priority when done; two consecutive passes start the Battle.
• Battle: cards act in SP order (15 → 0). When one of yours is up, pick Basic / Special / Skip, then click glowing targets. Multi-hit cards (⚔N×D = N hits of D damage) and barrage Specials take up to N picks — spread them across targets or repeat one to stack; it fires at the cap, or press Fire early. The badge on each of your tokens cycles its auto mode: MANUAL → AUTO (basic only, never spends pool) → FULL (may fire Specials).
• Win: wipe the opponent out (board + hand + deck empty) or hold / permanently capture all 4 of their Home slots. An invader that survives a full round on a Home slot captures it forever.

Architecture

src/engine   pure TypeScript, zero React — types, state, rules (legality),
             combat (damage pipeline + special-handler registry), phases
             (round loop + intent reducer + advance() driver), ai, rng
src/data     78 alpha cards as plain data across all 8 elements, grouped
             into four selectable decks (leaf_pyro, bore_dusk, aqua_dawn,
             gale_bolt) via the DECKS table; each card once per game.
src/ui       React only renders state and dispatches intents
src/engine/__tests__   Vitest suites for milestones 1–8, incl. full
             AI-vs-AI matches, determinism replay, and both win paths

All randomness (shuffles, coin flips, SP tie-breaks, CRIT/EVASION/SLEEP coins) flows through one seeded RNG in GameState.rngState, so any match replays exactly from its seed.

Alpha scope notes (deliberate)

• Per the alpha brief, this build uses a draw/hand model: shuffle, draw a 4-card opening hand, draw 1/round with a +2 bonus (draw 3) on rounds 10 and 15, no hand cap, play only from hand. Fixed 19-card decks; empty deck just stops drawing (no penalty).
• King of the Hill is IN: +1 DMG while in a Mid row, +1 board-wide per fully-controlled Mid row (tokens show live effective damage).
• Statuses follow the updated rules doc: BURN melts 1 shield per tick; FREEZE = SP 0 + half damage; WEAKEN = −25%; STUN blocks attack, move, and Special; SLEEP is a full skip until any hit wakes it; FRIGHTEN is a forced retreat (1 slot back if open) + movement lock, not a skip.
• Two deliberate deviations from the rules doc, per design rulings made in playtesting: melee reach is the 8 adjacent squares (doc says same/adjacent row with no column limit) and Specials have a 1-round cooldown (doc says no cooldown). The doc should be updated to match.
• Spells/Traps, Talents, EQUIP, and all auras except LEAF Photosynthesis (+1 HP end of round, the one alpha aura hook) are out of scope. GALE/AQUA/BOLT/DAWN cards aren't in the set, so their statuses exist in the engine but are mostly unused.
• Card adaptations from the source files (flagged in src/data/cards.ts): Alpha's conditional lifesteal → plain LIFESTEAL; Granite Armadillo's Curl Up → BLOCK 2; Clubber's coin-flip reflect → REFLECT 1; Widowbite gets STEALTH (as in the UI mockup) in place of its on-death passive; Rhe's Rigid Smash → 5 DMG + SLEEP one target; conditional-buff passives are dropped. Working passive surfaces: keywords, basic-attack status riders (onHitStatus), on-death retaliation (onDeath), on-summon effects (onSummon — free, fired through the same handler registry; a spread param projects a forward corridor toward the enemy — spread columns to each side, reaching one row for Melee or all the way to the enemy battlefield for Ranged, via forwardAreaTargets. Flamehound's Fire Blast = 3-wide far, Spitfire's Spit Shot = single-lane far, Fenrir's Fury Unleashed = 3-wide one row), Pumpkin's Catapult (ignoresHomeRule), Haunt's Jacked (drainMax handler), and Bearocks' Hibernation (statusImmune — negative statuses fizzle). Not yet: on-kill, on-being-hit, start-of-round spawns, token/minion spawning, and auras beyond LEAF's. Legendary specials that spawn tokens (Efy, Wraith) or move-and-strike (Skelider's charge) are simplified to their damage/status core for alpha; the flavor returns with the spawn system.
• Specials have a one-round cooldown (alpha balance change from the rules doc's no-cooldown wording — stops SLEEP/AOE spam): after firing, a card must sit out one full round before firing again.