The Daily Rift — seeded runs, one a day, with streaks and sharing

[FiddlyDigital]

The retention hook: a single seeded run per day against the same dungeon as every other player, with a streak to keep and a result worth sharing.

Two commits — the seedable simulation that makes it possible, then the feature itself.

1/2 — Seedable simulation (47fc7f5)

rng: () => number becomes a third injected port alongside now and stash:

new Game(cb, { seed: 20260731 })   // reproducible
new Game(cb)                       // unseeded, as before

All ~59 simulation-side Math.random() calls route through it:

• game.ts and the composed modules use this.rng() / this.game.rng()
• systems that already receive game use game.rng(); CombatSystem's private rollDie/resolveCombatRoll take an explicit rng parameter
• dataLoader's pure content pickers (shuffleInPlace, buildOffer, tierForFloor, Boon/Brand.pickThree, FloorEvent/Npc/Omen.random) take an optional rng defaulting to Math.random, threaded from the call sites

Cosmetic randomness in renderer.ts/particles.ts deliberately stays on Math.random — it never affects outcomes.

Two subtleties worth reviewing:

• Stream position survives a save. A PRNG's position isn't captured by a state snapshot, so resuming a saved daily would silently become a different dungeon. Game counts its draws (rngCalls, serialized) and restoreRngPosition() fast-forwards a restored run to the same point. rng/rngBase join SAVE_SKIP as live closures; seed/rngCalls are saved as run data.
• Unseeded runs resolve Math.random lazily rather than capturing the reference, so tests and hosts that stub the global still take effect on an already-constructed Game. (Eight existing tests do exactly this.)

New src/rng.ts: mulberry32 (makeRng), a stable FNV-1a hashSeed, and dailySeedString (UTC day).

2/2 — The Daily Rift (92f7d27)

• Start-screen button showing today's date and current streak; disables itself once the day is spent.
• Same dungeon for everyone, keyed off the UTC calendar date.
• Locked to default difficulty with no NG+ heat so scores are comparable — but class and curse stay player choices. The dungeon is what's shared, not the loadout.
• One attempt per day: the first result is banked; replaying neither double-counts the streak nor overwrites the record.
• Streaks advance on consecutive UTC days, reset after a gap, and keep a best-ever. Month boundaries handled by date arithmetic, not string maths.
• Shareable summary — the existing share box becomes a multi-line daily result (date, outcome, XP, kills/lines/combo, streak); normal runs keep the old one-liner.

launchWithModifier gained fixedDifficulty/skipHeat options rather than a parallel code path, so the daily reuses the whole existing setup flow.

Design note

I let players pick class and curse on dailies rather than fixing the entire loadout. Fully fixing it would make scores more strictly comparable, but removes the decision-making that makes a run interesting. Easy to tighten later if leaderboard purity matters more than variety.

Verification

npm run verify green: 456/456 tests (10 new seed/rng cases, 6 new streak cases covering gaps, month rollover and same-day replay), coverage ~86.1% stmts / 78.4% branches / 85.4% funcs / 88.9% lines, lint + validate-data + headless + build + smoke all pass.

Verified live in-browser: the Daily button renders today's date, and starting a daily correctly skips the difficulty picker straight to class selection, with no page errors.

🤖 Generated with Claude Code

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Generated by Claude Code