Corridor 7: Alien Invasion is a sci-fi first-person shooter developed and published by Capstone for the PC (running MS-DOS) in March 1994.
Set in futuristic 2012, the game takes place in a top-secret underground facility, run by the United States government, known as Corridor 7. After a team of scientists bring an alien artifact from Mars to deep inside the facility, a mysterious vortex is opened, leaving the base overwhelmed by dangerous aliens. A lone Special Forces agent (the player) must infiltrate the facility and stop the invasion.
The game was built on the Wolfenstein 3D engine (similar to their other game at the time, Operation Body Count) and was originally released in floppy disk format. An enhanced CD version was released on May 6th, 1995, containing more weapons, enemies, and levels, as well as added multiplayer and redbook audio support. A sequel to this game, called Corridor 8: Galactic Wars, was under development using the Build engine. It was canceled when Capstone went bankrupt. One of the programmers recently released the prototype to the Corridor 7 fan site, which can be found here.
Corridor 7 plays like traditional first-person shooters of the early 90s. One key difference is that the player must kill a certain number of aliens per level in addition to finding the exit for each level. The difficulty choice not only determines the number of aliens spawned, but the number of aliens required to finish each level.
- Corporal - Fewer aliens than normal. Only 10% of aliens must be eliminated to finish the level.
- Lieutenant - 75% of aliens must be eliminated to finish the level.
- Captain - All aliens must be eliminated to finish the level.
- Major - More aliens than normal. All aliens must be eliminated to finish the level.
- President - Only available in the CD version. Similar to the Major difficulty, only it features a customizable randomization factor that scatters all the items in the level.
The floppy disk version contains 36 levels (6 of them being secret levels). As the player makes his way through the levels, the architecture becomes more alien-like. The CD version contains 10 more levels that take place in the alien homeworld after the player enters the vortex. (Which have teleporters instead of elevators and no kill requirements) The CD version also contains 8 deathmatch levels for use in multiplayer games. (The first of those having a striking resemblance to the first level in DOOM)
Multiplayer in the CD version can be played in both regular deathmatch and team deathmatch. Because of the limitations of the Wolfenstein 3D engine, the firing animations always face forward. Players can choose between the standard marine or one of the aliens, which have unique speed and health.
There's an assortment of items to aid the player in his quest. For example, the player has a visor that is capable of infrared (to detect hidden enemies and traps) and night vision (for dark areas). The player's visor is also capable of showing an automap (known as proximity map) that shows a limited amount of the level. (Which can be expanded by collecting a Floor Plan item). The player can also collect and use proximity mines.
Other items that are scattered around to pick up are charge packs (which recharge alien weapons only), ammo packs (which increases your max ammo count), body armor (which gives you 200% armor), adrenaline bursts (which temporarily increases your health by 300%), and invulnerability spheres. Health can be replenished by both medic pack dispenser walls and special "health chamber" rooms. There are also dispenser walls for grabbing regular ammo and recharging your visor battery. Instead of keycards, the player activates a working computer which unlocks all the doors of that color (red or blue). But beware, some computers instead trigger the alarm (which angers the aliens).
The original game includes five weapons at the player's disposal, which use one of two types of ammo: Regular and Alien (which is found by Alien Packs). Players start with the Taser and the M-24 Close Assault Weapon.
- Taser - Weak, self-charging, fallback handgun that requires no ammo. It has very limited range and very slow rate-of-fire.
- M-24 Close Assault Weapon - Standard fully-automatic assault rifle that is good against weaker enemies in close-to-medium ranges. Uses regular ammo.
- M-343 Tri-barrel Power Blaster - Triple-barreled fully-automatic shotgun that can take out aliens at longer range without sacrificing power. Uses regular ammo.
- Alien Dual Blaster - Fully-automatic machine gun used by the alien forces. Functions similarly to the M-24 C.A.W., but consumes less ammunition per shot. Uses alien ammo.
- Alien Plasma Rifle - Powerful alien device (functioning similarly to a rocket launcher) that fires a large plasma ball that explodes upon impact, damaging everything within its blast radius. Uses alien ammo.
The CD version added three new weapons:
- Assault Shotgun - Standard pump-action shotgun that is deadly in close range and weak in long range. Uses regular ammo.
- Alien Assault Cannon - Fully-automatic assault cannon used by the alien forces. Functions similarly to the Alien Dual Blaster, but has a faster rate-of-fire. Uses alien ammo.
- Alien Disintegrator - A very powerful alien device that vaporizes every enemy in front of the player (at the cost of its ridiculously-high ammo consumption). Uses alien ammo.