How the destructible environment works?

[alfredoow]

Sorry for bothering, but github doesn't have a comment section for asking questions and so I had to use the 'Issues' tab. Anyway, can you please explain (or just point out the code of) how you recreated the "destructible environment mechanic"? I've been trying to remake it and can't find help anywhere. The tiles are 8x8 (like almost every other NES game), but somehow they can be reduced to little pieces? Can't quite figure out how. Again, sorry for bothering you for a 3 yr old project code, but I'm a huge fan of this game (it brings great childhood memories) and I'm trying to understand the intricacies of this marvelous 8-bit relic.