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Descent computer game

Descent is a 3D first-person shooter game noted for popularizing the use of portal rendering technology and providing the player with six full degrees of freedom to move and to look around. Descent spawned two direct sequels (Descent II and Descent III), and Descent:Freespace, an interstellar first-person war game. The source code to the original Descent (minus the networking code) was released in 1997. The source code to Descent II, III, and Descent Freespace has also been released and is available at http://www.descent-network.com

The original Descent game (made by Parallax) ran under MSDOS and was (with some tweaking) playable on 486-based PCs at 66 Mhz. With the release of the Intel Pentium, the performance requirements disappeared as an issue. Descent was ported to Apple's Power Macintosh in 1996 and both versions supported multiplayer network play over a variety of protocols.

Descent was released in 1993, a year or two after id's Doom but before Quake. Like those programs, it used a software renderer (3D graphics accelerator cards were not yet mainstream on the PC) and shared texturing similarities. Instead of using BSP trees, however, Descent's scene graph employed portals. In this scheme, the player progressed from one enclosed chamber to another, and since the chambers were linked by narrow doors or tunnels, it was a straightforward matter for the program to know that other chambers were unnecessary to render.

Perhaps the more significant improvement over Doom was that Descent used bitmap sprites only for powerups and not for opponents. With true 3D enemies, the game introduced a more frightening level of realism.

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The premise of Descent was that the player is the pilot of an armed spacecraft charged with rescuing humans taken hostage by renegade mining robots. The action always takes place in the mineshafts (as necessitated by the portal renderer). Exiting the mine required the player to locate and detonate the mine's nuclear reactor, causing the exit doors to open. It wasn't necessary to rescue any hostages, but a bonus accrued if one did.

The mines are owned by an allegedly evil megacorporation who hire the player to undertake the rescue missions. The mystery is that no one knows why the mining robots have become hostile. It takes until Descent III to find that out.


In the original Descent, there are 26 episodes corresponding to 26 different and unique mines (and also three secret episodes). The first three begin on the Moon, the fourth on Venus, the sixth on Mercury and then back out towards Mars and on towards the moons of the gas giants and finally until Pluto and Charon.

Each episode starts with the player in his ship materializing in a starting location within the mine. The player must then navigate through the mine destroying enemy robots and picking up powerups if his resources run low. Unlike Doom, where the player apparently never fatigued, the player's spacecraft had a fixed energy budget and required regular pickups of energy powerups to remain mobile. Killing opponents, however, often released such powerups. There were also permanent recharging areas available.

Like Doom, Descent provided a navigational wireframe map that would display any area of the mine visited or seen by the player. Since it was truly 3D, however, navigating the map could be challenging.

Although the keyboard interface for moving and rotating in full 3D space was easily learned, many players initially suffered from nausea and confusion since any viewpoint became possible. With practice, however, most people found the game fluid and very enjoyable. A bigger annoyance for casual players was getting lost in the mines (some of which were very large and complex). Highly experienced players who could memorize the mine layouts became adept enough to play the game continually upside-down, but if done for too long, this produced an awful disorientation effect when returning to the real world.

The enemy AI was touted as quite good (and perhaps it was for its day) but in practice was easily defeated. Although the object of simply blowing up robots and a reactor would normally be dull, the overall gameplay was enchanced by the wide variety of weapons the player could wield (and also learn to avoid). There was also the challenge of finding the reactor.

Dying wasn't so bad. Although one found oneself back at the mine's entrance, all the resources (weapons, etc.) acquired thus far would be strewn about the area of death waiting to be reacquired.

The seventh level (which was the end of the shareware version) and the final level are cited as the most difficult. Both have large monster robots that fire powerful weaponry and continually cloak/decloak themselves.


The original Descent used indexed 8-bit color in DOS's display mode 13h, using 320 x 200 resolution. The artwork was first-rate, although some textures popped or shifted when viewed from certain angles.


Descent II added more weapon types, more enemy types, different mines, laser-reflecting force field walls, and transporter areas. The most notable additions were the Guide-Bot, a companion robot the player could use to aid in navigation and other tasks, and the Thief-Bot, a fast-moving, hard-to-kill enemy that attempted to steal the player's resources. Graphics were still 8-bit but multiple resolutions were supported. It looked particularly good on the Macintosh.

Descent III switched to use accelerated 3D graphics hardware and improved the rendering engine to support outdoor environments with a nice automatic LOD terrain system. The rain effect in particular was nicely done. The higher resolution and renderer change makes the textures appear flatter, however, and thus the game seems less ominous than its predecessors.

Descent:Freespace also used 3D accleration. A main difference was that one could not slide the spacecraft, thus being greatly unable to dodge enemy weapons fire. As the action took place entirely in deep space, it was practically impossible to tell how fast one was moving and in which direction since there were no obvious frames of reference.

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