I am planning to make games for raspberry pi but I don’t have one to test, waiting for my pi now. I made a small performance test: a 3D-game where you can just run (buttons W and S) and rotate your camera (buttons E and Q), nothing else at all. It’s for Windows 10 ARM64/Windows IoT 64bit. You can find it here: Game test for Windows on ARM processor
If you check it out and it runs on RasPi, please provide feedback, I need it for further games.
Update: see this answer why I will not continue my tests.
Update 2: there is a very Unity-like game engine Urho3D that supports making game for 32/64 bit ARM Linux, including Raspbian OS. As Raspbian is the only optimized for the Pis, it seems that this is the best solution of making 3D games