Today I focused on procedural generation. I have a small playable demo of a procedurally-generated sewer. Walls are placed using wave function collapse, then sludge pools, bridges, doors, and the start and goal locations are chosen based on hand-crafted rules. I then spent an hour or so integrating the level generator into the RIP engine, and messing around with graphics and lighting.

Slime99

In the not-too-distant future, THE YEAR 1999 fallout from THE WAR has caused RADIOACTIVE MUTANT SLIMES to appear in the sewers of THE CITY. You are a GENETICALLY-MODIFIED PRECOG SUPER-SOLDIER, whose free-will was in-part traded for the power to PREDICT THE OUTCOME OF COMBAT ENCOUNTERS. Go into the sewers and ELIMINATE THE SOURCE OF SLIME!

The vertical scrolling effect in the original “The Legend of Zelda” relies on manipulating the NES graphics hardware in a manor likely that was unintended by its designers.

Since I don’t have access to any official documentation for the NES Picture Processing Unit (PPU - the graphics chip), my claim of “undefined behaviour” is somewhat speculative. I’ve been relying on the NesDev Wiki for a specification of how the graphics hardware behaves. The PPU is controlled by writing to memory-mapped registers. Using these registers for their (seemingly!) intended purposes, the following effect should not be possible:

Making an emulator for a 1980s game console is an exercise in reading and comprehension. The work is mostly translating documentation into code. It’s oddly satisfying, building a model of an ancient machine, instruction by instruction, device by device, especially once it can start running real programs. You end up with an appreciation for the capabilities (or lack thereof) of hardware at the time, and out of necessity, end up intimately familiar with the inner workings of a piece of computing history.

This post is not about making an emulator.

It is about the nightmarish, overwhelmingly complex, and at times seemingly hopeless task of hunting down the parts of your emulator that don’t behave exactly like the real hardware.