W,A,S,D or Arrow keys to move, click to fire in the direction of the mouse cursor. Spacebar or Ctrl to toggle sound
Energy is your current health and your weapon power. Get blue power ups dropped from special enemies to raise both. Getting shot or colliding with enemies lowers it.
S.LVL denotes how hard the game currently is. The better you do, the higher it goes.
Destroying special enemies also rewards a 100 points x the current multiplier level. Destroying enemys rasies it. Getting hit lowers it. Getting a powerup while energy is full will award 5000 points.
Scores and stats are submitted once the game ends(timeover or player death).
Game tips:
Regular enemies will usually spawn near the center of the arena. Special enemies however, will spawn from any angle.