Native Linux games work just fine under Wayland (KDE). Windows games now work too (under Wine/Proton) but isn't ready for prime time yet (although GloriousEggroll's Proton is in a much better shape though thanks to additional Wayland compatibility patches, but it's still technically beta). In saying that, games running in Wayland using XWayland run. mostly okay, but most performance-conscious folks might want to run them using Valve's gamescope microcompositor which usually delivers better performance and as a bonus, packs some nifty features like better HDR support, resolution spoofing and FSR scaling, which means you can upscale games on low-end PCs, or supersample older low-res games on modern PCs.