Ahoy there! I wasn't able to get your game running. On my desktop machine running Nvidia proprietary drivers, I get an error (not surprising - AFIK, kmscube isn't intended to work with them) saying:
"drmModeGetResources failed: Invalid argument
failed to initialize DRM"
On a laptop running Intel Sandybridge graphics with Mesa 18.2.2, I get a white screen when switching to a TTY and attempting to run it, which doesn't seem to respond to anything except Ctrl+C. When returning to the TTY, I see output that lists EGL and OpenGL extensions, but no indicators of problems.
I'm happy to invest a little time in getting things running, but I'd like to wrap up my impressions/feedback by tomorrow and may not be able to include KMSshooter.