A downloadable game for Windows
You have a gun, there are no win conditions. Also your gun propels you backwards because you skipped gun 101 at the gun academy for gun people and can't control your weapon.
Get skilled enough and you can fly in the air with your gun like a gun-jetpack or something.
WASD to move.
Left Click to fire
When not upright, A and D will rotate your player character.
Oh also the camera rotates loads so don't play if you get motion sick.