AI Models Attempt Prince of Persia Port from 6502 Assembly to C#

Experiment Overview

An individual conducted an experiment to assess the capabilities of frontier AI models in porting legacy game code. The task involved converting the 6502 assembly source code of the 1989 Prince of Persia game into a playable C# version. The experimenter provided only prompts to the AI models and did not manually edit the generated code.

Claude Opus 4.6's Attempt

In February 2026, Claude Opus 4.6 was given the initial prompt to convert the 6502 assembly code to C#. Over two days, the model produced a C# console game, a level editor, and a Raylib graphics version. It successfully parsed original level files and rendered visuals resembling the Apple II game. However, the game's core mechanics, particularly character movement, were incorrect, leading to issues like scrambled graphics and the prince not staying on the floor.

OpenAI Codex's Contribution

Following Claude Opus 4.6, an unspecified OpenAI Codex model was tasked with fixing the issues in the generated C# codebase. Codex implemented several minor improvements, such as sharp pixel filtering, transparent sprite backgrounds, and correct collision detection for gates and pillars. Despite these surface-level fixes, the fundamental movement problems persisted, indicating that the underlying game engine logic remained flawed.

Core Challenge: Game Mechanics

The primary difficulty encountered by the AI models was accurately replicating the game's movement architecture. The original Prince of Persia uses hand-drawn animation frames with small movements per frame, creating fluid motion. The AI-generated versions, particularly from Claude Opus 4.6, implemented a tile-based movement system where the prince hopped from cell to cell, which did not match the original game's physics and playability.