After publishing an honest platform review of RUN.world, I wanted to test the platform under real game jam conditions. The "Monster Mash" jam was live, themed around monsters, so I built and shipped Abomination Arena.

Most survivor-style games put you in the shoes of a heroic knight or wizard fighting off demonic hordes. I inverted that: you play a grotesque monster trying to survive endless waves of Ugly Humans swarming down from the surface.

In the middle of the arena sits Doctor Mittens—a fluffy cat surgeon. As you slaughter humans, they drop anatomical hearts. If you collect enough hearts and run back to Doctor Mittens in the center of the map, he performs surgery on you mid-run, stitching on body parts to boost your stats.

Here is the breakdown of what the game actually is, how the mechanics work, and how it was built through iterative prompting.

The game follows a classic bullet-heaven / survivor arena loop:

  • Movement & Auto-Attacks: You steer with WASD, arrow keys, or touch-drag on mobile. Attacks fire automatically at the nearest humans, so the skill is pure positioning, dodging projectiles, and managing crowd distance.
  • Scaling Pressure: Humans spawn faster and get tougher the longer you survive. Regular humans throw rusty hammers, while elite bosses spawn every 105 seconds throwing butcher knives.
  • In-Run Loot:
    • Gems: Provide XP for standard level-ups.
    • Anatomical Hearts: In-run currency spent at Doctor Mittens’ surgery.
    • Potions: Direct health restores.
    Pickups have a magnetic pull radius that can be upgraded.
  • Doctor Mittens’ Surgery: Running up to Doctor Mittens with enough hearts opens his body parts menu. You can buy upgrades for max HP, armor, regeneration, attack speed, movement speed, or luck. Each consecutive surgery costs more hearts than the last, forcing you to weigh the risk of wading into human mobs to harvest more.

Weapons & Synergies

Every level-up offers a choice of three weapons or upgrades (up to level 5 each). We built 17 weapons total:

  • Core Set (9): Bone Throw, Acid Spit, Eyeball Orbit, Stink Burst, Tentacle Whip, Eye Beam, Jaw Snap, Parasite Pets, and Tooth Nova.
  • Unlockable Set (8): Hazard Trail, Static Arc, Barbed Harpoon, Egg Pods, Vomit Volley, Evil Eye, Quill Burst, and Black Hole Maw.

A good survivor game needs a reason to play run after run. Everything outside the arena runs on Bones:

  • Earning Bones: Awarded at the end of each run based on your survival time, kill count, and level reached.
  • Creature Roster: Bones unlock four distinct playable monsters, each with unique baseline stats and starting weapons: Tentacle Mob, Abomination Hog, Rotting Unicorn, and Lobster.
  • Permanent Upgrades: Each creature has individual permanent stat tracks upgradeable up to Level 8 using bones.
  • Map Unlocks & Lifetime Goals: Defeating bosses unlocks new maps (currently Forest and Swamp, with more planned). Lifetime milestones (total kills, boss kills, weapon-specific kills) unlock the eight advanced weapons.
  • Monetization Hooks: RUN.world lets you wire up platform microtransactions natively. Bones can be bought with platform currency, earned through daily gift drops, or rewarded via opt-in rewarded ads.
  • Leaderboards: The main menu includes a global leaderboard for lifetime bones collected, plus individual per-level boards for best survival time showing the top 10 and the players around your current rank.

The aesthetic rule was simple: dirty, used, rusted, and bloody.

  • UI & Menus: Generated art depicting rusted iron walls, rotting wooden planks, and riveted plates for all buttons.
  • In-Game Models: Simple 3D shapes with thick outlines. Projectiles aren't generic spheres—they are modeled as flying rusty hammers, butcher knives, harpoons, and egg pods.
  • Feel & Feedback: Getting hit triggers screen flash, camera shake, and floating damage numbers. When your health drops below 25%, a dense blood fog creeps in from the edges of the screen.
  • The Death Sequence: When you die, the camera spirals slowly around your collapsed corpse while the human horde continues to beat on you, before transitioning to the score summary.

The game wasn't generated in one magic prompt. It was built conversationally, step by step, testing the build after every single change:

  1. Prototype First: Started with a barebones survival loop—one creature, basic auto-attack, placeholder pickups, and the Doctor Mittens shop.
  2. Modular Weapon Architecture: The 17 weapons were written with one file per weapon. This modular structure prevented the AI from breaking existing combat logic when adding new projectiles.
  3. Discarding Features That Sucked: We initially hooked up a phone-vibration effect on player damage. In theory, it sounded tactile; in practice, late in a run when dozens of mobs hit you, your phone turned into an annoying massage gun. I cut it immediately.
  4. UI Stabilization: Early leaderboard screens jumped around while fetching scores. I had the AI lock down the UI into fixed-size grid boxes so the screen layout stayed completely stable during network requests.
  5. Onboarding: After an automated code review showed that first-time players might be confused by the Doctor Mittens surgery loop, we added a skippable 4-step interactive intro explaining movement, auto-attacks, loot, and surgery.

The game is live and playable at run.world/evgenii_zinner/abomination-arena.

Because it was built during a jam, balance is still raw: damage scaling, boss health pools, and human spawn pacing haven't been calibrated against large-scale player telemetry yet. A few legacy emoji placeholders still need replacing with painted assets.

"AI game tools won't design a good game for you, but as a rapid iteration partner for a solo dev, being able to scaffold 17 weapons, boss timers, upgrade trees, and global leaderboards in a single weekend is a game-changer."

For an architectural overview of how RUN.world's SDK, CLI, and creator revenue model operate, see the companion review: Building Games on RUN.world: An Honest Review for Creators.