Nightfall - The Kingdom That Raids You Back

Build your keep by day, commit one raid, and log off. Every night the whole subreddit's raids resolve at once so you always come back to see what happened while you slept.

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Inspiration

The best Reddit games aren't things you play; they're things you check. r/place, the button, Twitch-plays experiments. They work because the community moves while you're gone, and you come back to see what changed.

We wanted that feeling in a strategy game. Not another tap-to-win clicker that begs you to stay, but a game with a hook that pulls you back tomorrow: you commit an action tonight, and the outcome literally doesn't exist yet. So the only way to find out how your raid went — and who raided you while you slept — is to come back.

That's Nightfall: the kingdom that raids you back while you sleep.

What it does

Nightfall is an asynchronous kingdom-raiding game that lives entirely inside a single Reddit post. The loop is deliberately tiny:

  1. ☀️ By day — spend 5 Action Points fortifying your keep: raise your Wall, stash gold in the Vault (un-stealable), build a Generator for income, a Watchtower to scout, or arm Spike Traps.
  2. 🗡️ Commit one raid — pick a target from the Raid Board (someone in your league or richer, or an NPC bandit camp), choose your party size, throw in a taunt, and lock it in.
  3. 🌙 At 20:00 UTC every night, the entire subreddit resolves at once. Every raid, everywhere, in one deterministic batch.
  4. 🌅 The next morning opens with a Dawn Recap — an animated battle replay of exactly what happened to you overnight, whether you logged in or not.

There's no "win screen." It's a persistent ladder across leagues (Bronze → Silver → Gold → Obsidian), surfaced as your Reddit user flair. When someone breaches your wall, a one-tap Revenge raid (+20% loot) targets them right back — so two players end up returning every single day because of each other.

The whole economy is built to pull you back: daily streaks (with a weekly streak-freeze), Action Points that refill each night, leagues with weekly promotion, one-tap revenge that expires, and a Dawn Report comment that recaps the night for the whole sub. Miss a day and you fall behind; show up and you climb.

How we built it

Nightfall is built on Reddit's Devvit Web platform, 100% in TypeScript, with a clean three-layer split:

  • shared/ — the single source of truth. Every balance number lives in one config.ts, all domain types in types.ts, and a deterministic seeded RNG (xmur3 → mulberry32) that makes the whole game reproducible.
  • server/ — a Hono app running on Devvit's serverless Node runtime, with all state in Redis (no SQL). The heart of it is resolve.ts: the nightly resolution algorithm that loads every player, shuffles all committed + NPC raids, resolves each battle (traps → defense → breach/pyrrhic/repelled → loot → bounty payout → revenge setup), and emits the report.
  • client/ — a React 19 + Tailwind UI with two entrypoints: a lightweight inline splash shown right in the feed, and an expanded game view. The battle replays are rendered in Phaser 3 — a procedurally drawn night siege with torch-lit keeps, marching soldiers, arrow volleys, and a camera shake on every breach (no image assets).

The nightly batch runs on the Devvit Scheduler (0 20 * * *), the weekly season rollover on Mondays, and the Dawn Report is auto-posted as a comment on the game post — a daily town-square recap of the night's biggest heists.

The trick that ties it together: the RNG is seeded on the date string. Because the server and client share the same seed, the client can rebuild the exact same battle the server resolved — beat for beat — so the Phaser replay is a faithful re-render, not a fake animation.

Challenges we ran into

  • The onboarding paradox. A game whose whole point is "come back tomorrow" is brutal to demo — a new player shouldn't have to wait 20 hours to feel the loop. We solved it with a 60-second tutorial expedition: a new player's first raid resolves in ~60s via a one-off scheduled job, so you experience the full commit → resolve → recap arc inside your first session, then learn the real cadence is nightly.
  • Snowballing. Async raiding punishes people who log in less. We layered in anti-snowball systems: a Vault floor of un-stealable gold, honor matchmaking (raiding down earns 90% less loot), a one-night post-breach shield, per-target raid caps to stop pile-ons, underdog income bonuses, and a soft weekly season reset.
  • Empty mornings. In a small subreddit, nobody wants to wake up to "nothing happened." Deterministic NPC bandit camps guarantee there's always a target, and they auto-raid inactive players so no Dawn Report is ever empty.
  • Determinism. Making the client replay match the server resolution exactly meant every random draw had to flow from one seed in one order. Getting that airtight (and unit-testing it) took real care.

Accomplishments that we're proud of

  • A genuinely async social hook that needs no notifications to work — the game moves while you sleep, by design.
  • Server-authoritative battles that the client replays exactly, via a shared seeded RNG.
  • A full anti-snowball / retention economy, live-tunable from Redis with zero redeploy.
  • Zero external API calls — fully compliant with Devvit's rules and entirely self-contained on Reddit.

What we learned

  • The best Reddit games design around absence, not engagement — what happens while you're gone is the product.
  • Determinism is a feature: seed everything and your "netcode" becomes trivial.
  • Onboarding for an async game is a separate design problem from the game itself.

What's next for Nightfall

  • Alliances — shared war rooms and coordinated multi-kingdom sieges.
  • Seasonal events — blood moons, sieges, and limited-time modifiers.
  • Deeper Reddit integration — comment-driven taunts, subreddit-vs-subreddit wars, and flair-based rank cosmetics.
  • Spectator Dawn Reports — a public daily thread the whole sub can follow, even non-players.

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