For some reason this game only displays a blank window with audio for me. This is apparently a known Godot bug, and while most workarounds did not work for me, I was able to play FLEB's "20 Small Mazes" thanks to him switching from GLES3 to GLES2, which I'd read worked if the game did not require GLES3-specific stuff. So, if you feel like it, please see if you could try that :)
EDIT: Just in case someone else has a game only display a blank window with sound (bug from Nvidia clashing with Godot if I understood well), this trick solved it for me (Windows 7): type "cmd" in the game's address bar in the explorer, then in the console type "[game].exe --video-driver GLES2"