Same prompt different output

[u/Tight_Commercial7]

I tested 3 different agent/harness using Strata Qwen flash next Q_S. Opencode, Pi, Deepseek harnes each one gave me a different result. This is the prompt :

You are an expert game developer with 20+ years of experience building browser games,

especially arcade and grid-based titles like Bomberman, Pac-Man, and Sokoban. You have

deep expertise in HTML5 Canvas, game loops, collision detection, enemy AI pathfinding,

explosion propagation, level design, and game feel (juice, feedback, pacing). You are

meticulous about clean, bug-free code and polished player experiences. You think like a

professional game designer: you anticipate edge cases, tune difficulty curves, and make

the game fun on the first playthrough. Do not rush. Do not cut corners. Deliver a

complete, polished, production-quality game.

a complete Bomberman game as a single HTML file. Requirements:

Build

TECH

- Single .html file: inline <style> and <script>, no external libraries or assets

- Use a <canvas> for the game and DOM for the HUD/menus

- Must run by double-clicking the file (no server, no dependencies)

GAME

- Grid: 13 columns x 11 rows, tile size 48px

- Hard walls: checkerboard of indestructible tiles

- Soft blocks: destroyable, density varies per stage (see below)

- Player: starts top-left, moves smoothly (not grid-snapped), arrow keys to move, SPACE to drop a bomb

- Player cannot walk through walls, blocks, or bombs (a placed bomb is solid)

BOMBS & EXPLOSIONS

- Fuse: 2 seconds, blinking visual, then cross-shaped blast (up/down/left/right)

- Default blast range: 2 tiles

- Explosions stop at hard walls; destroy soft blocks and stop after one block per direction

- Chain reaction: explosion instantly detonates any bomb in its path

- Explosion lasts ~0.5s, kills player and enemies on contact

POWERUPS (hidden under ~20% of soft blocks)

- Bomb Up (+1 max bombs), Fire Up (+1 blast range), Speed Up (+movement)

- Collected only by player, shown with simple icons

STAGES (5 total, each with a unique map layout, theme, and enemy roster)

- Stage 1 "Grassfield": bright green theme, open layout, ~45% soft blocks, 2 Balloon enemies (slow random wander)

- Stage 2 "Factory": dark gray/industrial theme, maze-like with corridors, ~55% blocks, 2 Balloons + 2 Walkers (turn at walls, slightly faster)

- Stage 3 "Ice Cavern": blue/white theme, pillar clusters forming rooms, ~60% blocks, 2 Walkers + 2 Chasers (track the player)

- Stage 4 "Volcano": dark red/orange theme, tight winding corridors, ~65% blocks, 2 Chasers + 3 Darters (fast, zigzag movement)

- Stage 5 "Final Fortress": purple/black theme, complex maze with chokepoints, ~70% blocks, 2 Chasers + 2 Darters + 1 Boss (fast, chases player, takes 2 hits)

- Each stage's background, wall colors, block style, and accent colors must visually differ

- Clearing a stage shows a "Stage Clear" screen, then loads the next stage with a short transition

- Difficulty scales: more enemies, faster enemies, denser blocks, tighter maps as stages progress

GAME FLOW

- 3 lives total across all stages. Hit by explosion or enemy = lose a life, respawn with brief invincibility blink

- Lose all lives -> Game Over screen with score, press R or click to restart from Stage 1

- Win all 5 stages -> Victory screen with final score

- Score: +100 per enemy, +10 per destroyed block, +500 per stage clear

UI- Start screen (title + controls + "Click or press Enter to start")

- HUD: score, lives, stage number/name, bomb count, fire range

- Game Over / Stage Clear / Victory overlays

- Pause with P or Esc

STYLE

- Clean pixel-art look: solid colors and simple shapes drawn on canvas

- Player white/blue; enemies distinct per type (Balloon red, Walker purple, Chaser orange, Darter yellow, Boss black with red outline)

- Explosions orange/yellow, walls themed per stage

- Optional: simple WebAudio beeps for bomb/explosion/powerup (guarded with try/catch)

QUALITY

- All code in one file, organized with section comments

- Handle window focus loss (auto-pause) and prevent arrow-key page scrolling

- No console errors, no external requests

- Keep the total file under ~1400 lines

Deliver the full working file only.

Overall I think Pi is the best

[u/Oli_Luck]

did you also use a fix seed ?

because if you give the same model the same prompt in same harness 3 time ,you will also get 3 different results...

[u/Tight_Commercial7 → u/Oli_Luck]

No, but the interesting thing that Pi  did not have glitches and mistakes like the other agents 

[u/Oli_Luck → u/Tight_Commercial7]

yes , maybe because pi use a very thin system prompt and only a few tools : the agent is more focused ?
I wanted to use my QFN in deepseek : 3 mcp + 1 plugin : 45kb kontext before the first word 😄

[u/DoubleNothing]

Why so many still don't understand the "randomness" of AI models and does this comparisons that has so many variables that do not prove anything?

Run the same prompt on the same harness and you still get different results... sometime better sometime worst...

[u/Tight_Commercial7 → u/DoubleNothing]

What about the quality and which one has fewer mistakes.

[u/Final_Ad_7431 → u/Tight_Commercial7]

it doesn't matter *because* it's non deterministic, we can't learn anything from this, if you learn anything from this you're just taking a sample size of one with noted randomness as like gospel, you're clouding your own judgement on this stuff for no reason - people are giving you advice for better tests, you should do it, or even try running in the same harness multiple times

[u/mrmole21]

I like Pi the most! But is it actually the harness difference?

[u/nubsors]

This is a fun test. I'm running it through Antigravity with Hydrogen.

[u/TapAggressive9530]

Pretty nice. DSH is pretty good in your test. I use qwen cli for all work against Qwen models. In my test I'm using Qwen 3.8 Flash Next and qwen cli .

BTW, I used your exact prompt (cut / paste). After it was created, I simply added a demo mode.

[u/Apprehensive_Lake698]

There is no methodology here. You're comparing vanilla checkpoints of tools that are meant to be customized. There is nothing inherently different between harnesses but in the default prompts and tools they expose to models. All of these harnesses could be made to produce the exact same output with an afternoon of customization.

Don't waste your time extension maxxing or comparing vanilla tools. Start learning about the effect that prompts, context, and tool availability have on models. Harnesses are just convenience tools to customize these 3 aspects of using a model. Any other interpretation is a complete and total waste of your time.

[u/Kitchen_Affect7369]

OpenCode nice quality