Nah, it’s literally just Arch Linux with the tweaked Linux zen-kernel, a crap ton of eye candy and a few GUI tools.
You could use the zen-kernel on a plain Arch base add their GUI tools (likely just by adding their repo to pacman.conf) and likely achieve better results/performance because you’re not using resources on the flashy desktop effects and background processes instead having more available for the game.
Better yet, you could start with Garuda and strip it down and disable much of the resource heavy effects and achieve the same thing more or less.