*If game screen is messed up...Place mouse on game screen and right click. Then choose 'show all'.

The objective of the game is to move forward and keep killing the hostiles that want to prevent you from advancing. Upgrade your favourite weapons or health at each checkpoint. This will help you get more firepower and get further in the game.
A strategy would be to keep upgrading a particular weapon so it gets souped up. Upgrade your health only when you have low health.
Move Left, Right A, D Use shield S Select Weapon 1, 2, 3, 4 Reload R Throw Grenade Space Bar