Area 51

This game takes the player through several sections of the facility, including a warehouse and tunnels. The player character is tasked, along with fellow Special Tactical Advanced Alien Response (STAAR) members Lieutenant Stephanie Grant and Sergeant Major Marcus Bradley, to penetrate Area 51 and activate the nuclear self-destruct sequence. The player must defeat genetically modified zombie soldiers and aliens without harming any allied STAAR team members. If nothing but three STAAR team members are shot, the Kronn Hunter mode is started, taking the role of a Hunter, sent by the Kronn to eliminate the rebels.[5]

There are five types of weaponry available. While the player is only given a semi-automatic pistol in the beginning, weapon upgrades are available as targets. The pistol can be upgraded to an automatic machine gun, a pump shotgun, and finally an automatic shotgun. The shotgun weaponry allows a greater field of error for targeting an enemy. Both the machine gun and automatic shotgun allow the player to keep the trigger pressed down to unleash rounds. If the player character is hit by the enemy at any time, the weapon is downgraded back to the pistol.

Grenades are hidden in crates and bonus rooms. When used, they destroy most on screen enemies at once. The player can hold a maximum of nine grenades. In addition, yellow boxes and barrels marked with "flammable" warning symbols can be shot to cause fires or explosions that can harm enemies. By shooting certain objects in the correct sequence, players can unlock shooting exercises, weapon stashes, and bonus items that are not available in the main game plot. Other backdoors allow players to warp ahead to later levels instead of following the game's otherwise linear path.

There are many types of aliens/alien zombies including ones that shoot, punch, fire rockets, and throw things like bricks, grenades, and barrels. Purple alien/alien zombies require more hits than other targets.