TT Isle Of Man 3: Ride on the Edge - Gameplay and Settings - Steam Deck
Settings at: 3:45
Unfortunately, the game doesn't run that well. I would highly recommend getting TT Isle of Man 2 instead of the 3rd one here.
The game has a really difficult time handling shadows and keeping a stable frame rate. The only way I could get it to be "playable" was to disable the shadows and turn only FXAA on in the Post Processing effects, which compared to TT2, TT2 looks/performs better on the Steam Deck.
TT3 is a little more forgiving when it comes to going over curbs/dirt and I feel like the bike is more planted on the ground, collision is better when bumping up against other riders, but those minor improvements aren't worth the performance decrease when compared to TT2.
*When performance dips it feels like it messes with the physics and handling of the bike, making it almost impossible to be consistent in low performance areas.
Steam OS