Seems to run fairly well. Has Platinum/Gold protondb ratings for most releases:
Bloons TD 6 www.protondb.com/app/960090
Blooms TD 5 www.protondb.com/app/306020
Bloons TD Battles www.protondb.com/app/444640
Bloons Monkey City www.protondb.com/app/1252780
Bloons Adventure Time TD www.protondb.com/app/979060
Bloons TD Battles 2 www.protondb.com/app/1276390
Bloons Card Storm www.protondb.com/app/2876550
felsiq@piefed.zip 1 day ago
Really? I could’ve sworn I’d played that on Linux before, unless it’s been a lot longer than I thought since I touched it. Are we talking BTD6 on steam specifically?