The game involves the use of several guns and tactics. Your primary objective is to defeat your partner as soon as possible. It has two modes, the campaign, and the custom mode. You can select the mode you want according to your ability. It can be played by 1 to 4 players using various computer keys.
For two-player mode, the first will use the arrow keys and G-keys to play as other partner uses W, A, S, D, T and Y keys. The more you complete the chapters, the harder the game gets. The space bar is used to pause if you wish to have a break. You can then invite and play with the third and fourth players if they want to join through adjusting some settings in the options tab. It also has the gun library where you can test all weapons.