headcrab (its like h3adcr-b or something on the git) to install and update slssteam and prevent steam client from updating beyond compatible versions, add game appid to config file, put the game files where steam would normally install them, launch from steam like a purchased game. dlcs work without needing to bring your own files if you put the appid in the same config file. if you also use another piece of software called slscheevo and make sure the steam api dll file is unmodified, achievements also work and in most releases the unmodified one is backed up next to the patched one.
I haven't tested on actual steamos but it works on my bazzite deck as well as on normal distros. I find it far less troublesome than bottles/lutris/heroic or manual prefixes and its the most seamless once set up. Also bypasses family share restrictions and I've tested 4 players on one copy of a purchased game in the same multiplayer lobby.
So after looking at it and pulling it apart and several times missing the window to go look as its happening, it looks like it wasnt extruding enough to actually stick, eventually there is enough of a ball that it sticks and it repeats causing that pattern.






followed by "I never talked to anyone about that" or similar