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Side-by-side browser game at four effort levels

by Sinda | SKatalyst AI (@SKatalystAI) · Sep 25, 2026

What happens if you give Opus 5.5 the exact same game prompt and change only the effort level? Same model. Same task. Fresh session every time. Zero intervention. Low vs Medium vs High vs Xhigh. The difference was way bigger than I expected: LOW → 4m35s · $0.79 →Built a working game fast. MEDIUM → 14m31s · $2.38 → Started testing in Chrome, stress-testing FPS, fixing bugs and improving controls. HIGH → 31m43s · $6.04 → Turned it into a real product: better movement, bosses, richer combat, mobile polish, balancing, screenshots, performance checks. XHIGH → 1h17m · $9.35 → Basically became its own QA + game-design team. It created different player bots, realized its first bots were unrealistically good, redesigned the difficulty curve, retested, found UI/touch bugs, fixed them, and kept iterating until human-like bots died around the intended point. The simplest way I can describe it: >Low builds. >Medium tests. >High productizes. >Xhigh challenges its own work. So effort is not just “more thinking” It can completely change how the model behaves as an engineer. Video is the same prompt, side by side. 👇
— Sinda | SKatalyst AI (@SKatalystAI) Sep 25, 2026

Prompt

The author shared the full prompt.

Build a polished, playable browser game from scratch. Create a single-player neon survival game where the player controls a ship inside an arena. 
Use only vanilla HTML, CSS and JavaScript. Put the complete game in a single index.html file. 
No external libraries, external assets, CDNs or generated image files. 
Requirements: 
-keyboard movement 
-enemies that spawn and chase the player 
-shooting 
-collision detection 
-health 
-score 
-progressively increasing difficulty 
-game
-over state 
-restart 
-polished HUD 
-animations 
-particle effects 
-responsive layout 
-clear controls/instructions 
The visual design should feel intentional and production-quality, not like a basic demo. 
You may choose all other implementation and design details yourself. 
Do not ask me questions. Build it, test it, fix anything you find, and stop when you believe it is ready to ship.

Prompt by @SKatalystAI, from their reply

Category: Games
From the author: Fresh session each time; low, medium, high, xhigh comparison.
On X: 44 likes · 3K views · 9 saves

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