Seems like the OAM data for the title screen is pre-stored into memory at 0x600. Then copied on demand.

If the length byte has bit 6 set then it’s a repeating tile.

So yeah. Backgrounds are made up of strips. Each strip has a screen location, data length, and the strip data. The data is copied straight to the PPU.

I tell myself I can do just one simple thing at least I'll have advanced a little. Chips help with motivation.

Careful about those bakeries. Some of them are full of nothing but pain.

Next time I'll identify which mode is what.

According to this the game has 7 general modes, of which I've identified the title screen. The unknown ones could be the level intro walk-in animation, room-to-room transitions, game ending, stuff like that. Each mode has a set of init functions. Some sets are shared across modes.

So anyway, got an ugly version up (as seen above) and running and it looks like it's working fine. So that's kinda neat. Had been avoiding doing it for the past weeks because holidays and laziness.