Roguelike Deckbuilder

What it is. A run-based game where your deck is your build. You start with a weak pile, and after each fight you draft a card (usually 1 of 3, with a skip) — so the deck becomes a strategy over the run. Fights are the pressure test; the draft is the decision.

Player fantasy / why it’s fun. “I built this engine one card at a time and watched it come online.” The pull is the draft with teeth: each pick is a commitment, synergies compound, and a deck clicking into a combo is the payoff.

Pillars

Drafts with teeth. The reward-of-3-with-a-skip is the core decision. Picks must matter — the same pilot drafting off must lose far more (the 17→9 delta). If any card is fine, drafting isn’t a skill.
Spikes are blockable in principle. Incoming damage must be answerable — spike dmg ≤ block ceiling + heal — or a fight is a coin flip, not a puzzle. Perfect telegraph honesty: what’s shown is exactly what resolves.
Balance is a win-rate window. The health instrument is a range (e.g. 11–19 of 20), not a target. Both edges break: too-easy AND too-hard are bugs.

The loop stack

Scale	The beat
Moment	Play a card from hand: read the telegraph, spend energy, resolve — the choreography returns.
Encounter	A fight: your deck’s engine vs an enemy’s telegraphed intents; block/attack/status math.
Session	A run: map choice → fights → draft rewards → shape the deck → boss. Thin vs wide is the arc.
Meta	Unlock cards/characters, add to the pool; carry archetype knowledge between runs.

Essential systems

System	Why it’s load-bearing
`system-build-diversity`	Multiple viable deck archetypes; the reason to re-run. Making many strategies work.
`system-reward-schedules`	The card-reward-of-3, relics, shop, rare drops — the draft cadence and its pull.
`system-status-effects`	Poison/block/vulnerable/strength — the stacking rules that create combos.
`system-telegraphs`	Enemy intents shown ahead; the honesty that makes fights plannable, not luck.
`system-procgen-design`	Seeded map, reward, and enemy variance — each run a fresh hand of choices.

Content & difficulty model

Content is the card pool + relics + enemy intents. Depth is interactions (synergy engines), not raw card count. A small pool with deep combos beats a big pile of vanilla cards.
Tune the goal to the measured win-rate, not mechanics to a fixed goal — run a greedy pilot, place the window, adjust rewards/enemy math to land inside it.
Draft delta is the proof. Same pilot, drafting on vs skipping, must show a large gap (17/20 vs 9/20). If null drafting competes, the draft is decorative.
Intent honesty is a one-line audit. Resolve each telegraph, compare to the shown number — they must match exactly (law 6 / perfect-info honesty).
Meta adds cards, not power. Unlocks widen the pool; guard against the deck being decided at the menu. See system-meta-progression.

Signature-mechanic seeds

Deckbuilder but hands score like poker (mechanic-swap) — Balatro’s bend: the multiplier engine, not the fight, is the number-go-up. Pairs anchor-balatro.
Deckbuilder but the enemy drafts from your discards (structure) — your cast cards arm the boss; deck-thinning becomes a defensive art.
Deckbuilder but one card, played, is gone forever (constraint) — a scarcity deckbuilder; every play is a spend, hoarding stalls you.
Deckbuilder but cards are inked and fade (theme + tonal) — inked duotone cards that wear with use; the deck is a weathering artifact.
Deckbuilder but two players share one deck (perspective + coop) — alternating draws, one strategy; drafting is negotiation. Pairs system-coop-and-competition.

Common pitfalls

Every card is fine. With no bad picks, drafting has no teeth. Some cards must be traps in the wrong deck.
Unblockable spikes. Damage past the block ceiling turns fights into coin flips. Keep spikes answerable in principle.
Single dominant archetype. If one build always wins, system-build-diversity failed and replay dies.
Dishonest intents. A telegraph that resolves to a different number breaks the plannability the whole genre rests on.
Balancing to one edge. Tuning only against “too hard” ships a too-easy game; the window has two walls.

Anchors

anchor-slay-the-spire — the reference: draft-of-3, map choice, deck-as- evolving-strategy. Steal the whole spine.
anchor-balatro — the score-multiplier variant; steal the joker-synergy “number goes up” juice for a scoring-first bend.

Verify

Prove it in FUN.md §11 · Roguelike deckbuilder: a greedy pilot lands in the win-rate window, a never-draft pilot falls below it, the intent audit matches, and a golden climb hash replays.

Composes with

system-build-diversity — the multiple viable archetypes that carry replay.
system-reward-schedules — the draft cadence and its ethical pull.
system-status-effects — the stacking rules that make synergy engines.