This one's not exactly buggy, but it's barely playable for some other reasons.
1. The crosshairs seems like a feature that was intended for aiming, but your bullets travel in the direction the tank is pointing instead of where your crosshairs is pointing.
2. The camera is zoomed way in on the action, too far to actually have enough time to point your tank sloooooowly around (sometimes nearly 360 degrees) before you eat a couple hits from aliens.
3. The tank just straight up doesn't control like a tank. You hit the spacebar to rotate (A and D should do this) and WASD hovers the tank around the level. This scheme is more like Asteroids, which makes no narrative sense for a game where you're driving a tank across a field blowing up aliums.