[alecu]

Spiral Tunnel's walls get the two-layer treatment the Catch the Robots maze got in #183.

Why

On a TUNNEL layer the renderer walks a tile column one texel row at a time, and several rows can land on the same LED; the last one drawn wins. Spiral Tunnel's brown fill and its one-pixel yellow edges (and the rocks from #183) shared one tile strip. Where rows bunched up, toward the middle of the disc, the fill drawn after an edge or a rock covered it, and the edges broke up.

What

The walls are now two tilemaps over the same cells, scrolled together:

• tiles.png: the plain brown fill.
• details.png: the yellow edges and the rocks on a clear background, drawn over the fill.

Nothing in details.png draws after an edge or a rock, so they always show.

• Each strip has all 35 frames, so both can read the same cells. That costs one more strip, about 2 KB.
• Together they paint exactly the old tile strip; make_art.py checks out pixel for pixel. So the menu icon is unchanged.

Tests

• New test: the details tilemap shares the fill's cells, draws after it and before the sprites, and scrolls with it.
• Suite and build: tests/test_ld60_games.py passes and mpy-cross compiles the game.
• Web emulator: the yellow edges run unbroken right down to the centre of the spiral, and the rocks show all the way in.

🤖 Generated with Claude Code