Enter does not paintings in fullscreen mode?

i have installed 2 games through lutris. each of them work pleasant but best in windowed mode. if i allow fullscreen mode by way of urgent “alt + input” then enter from my keyboard and mouse does not paintings. https://testmyspeed.onl/
despite the fact that i allow fullscreen mode from the settings, it stays the identical, keyboard-mouse does not seem to work in any respect in fullscreen mode.
how to resolve this problem?