gamescope is a micro-compositor with a lot of great features and a major advantage for gaming on linux
many games benefit from specific gamescope flagsets, here is my list
gamescope -eU -w1280 -h720 -- %command%
Select screen setting "1024 x 768" in OPTIONS.
gamescope -en -w1024 -h768 -- %command%
gamescope -in -w640 -h480 -- wine seiklus.exe
gamescope -e -r60 -w1920 -h1080 -- %command%
gamescope -ein -w640 -h480 -- %command%