It feels weird rereading my posts from 2016.... What a newbie! Anyway, I see a new problem (I adapted this code for the GitHub version of Sonic 1). I noticed this late, but when I enable the "Water_Flag" for example Marble Zone or whatever, Chunk n°0 (The big empty transparent square on SonLVL) is detected as solid in game. My little Ashuro hangs on an invisible wall when he touches the Chunk n°0. When I desactivate the water (and thus the Water_Flag and the check if it is this level? if yes initwater), this bug disappears and the transparent chunk become not solid again. I'll try to fix it myself and find a solution and I'll give it here if I find it, in which case if by chance someone has a lead, it's also welcome. Edit 1: same state as previous... If anyone is here ?