Alien Breed 3D

Alien Breed 3D is a first-person shooter in which the player fights their way through a military base on a fictional planet that has become infested with hostile aliens, with the goal being to reach the base's shuttle and escape. Across the game's 16 levels, the player must utilise their arsenal of weapons to kill the aliens, which include red doglike creatures, various gunned aliens, a class of hovering aliens, and "tree creatures who spawn flying eyeballs". The player begins the game with a pulse rifle, and four others, a double-barrelled pump-action shotgun, a plasma gun, a grenade launcher, and a rocket launcher, must be located and picked up. The player must also find supplies of ammunition to replenish their respective weapons' stocks.

As the player progresses, their character may sustain damage. Picking up a health kit heals the character.

Osiris III's commanding officer, Captain J. T. Reynolds contacts Earth Defense Force General R.E. Grant reporting how the secret Project Osiris has slipped out of scientists' hands: attempts have been made to cultivate the alien eggs found in Azirin by cloning them and combining with human DNA, leading to remarkable results, but due to system failures, the Breed has been unleashed and killed people at the research station. In the message, Reynolds announces that he has found weapons and other supplies in a decommissioned observatory and plans to return to the base to find an escape route from the planet and possibly destroy the Breed's source in the meantime before his own oxygen supplies dwindle.

Team17, a British game developer and publisher known for its Alien Breed series, considered 3D follow-up instead of the top-down view of its predecessors. It was planned to be MS-DOS-only, but the arrival of id Software's Doom led to the team not pursuing its development. The origins of Alien Breed 3D can be traced back to the University of York, where Andy Clitheroe, then a mathematics student, observed his peers being impressed by Doom. This included Clitheroe's girlfriend, his future wife Jackie, who was introduced to the game by a friend who bought a copy. Clitheroe sought to impress her by attempting a take on the popular shooter.

A friend of Clitheroe reverse engineered a demo to create an algorithm that would emulate a number-per-pixel mode on Amiga 1200, which relied on planar graphics for display. Number-per-pixel algorithms were favoured by other Doom clones for the Amiga for the convenience of changing the colour of each individual pixel, and Clitheroe used his friend's technique to create a first-person engine by himself. By chance, Team17's creative director, Martyn Brown, read a message on the Internet by the York student about his engine, which, at the latter's girlfriend's pressing, was then demonstrated in the company's offices on an Amiga computer. Brown became convinced that a clone of Doom for the Amiga could be made, and Team17 immediately hired Clitheroe and acquired his engine.

According to data from the European Leisure Software Publishers Association, in its first month, the game was the second-best-selling full-price Amiga game, behind Team17's own Worms. It was also the best-selling Amiga 1200 game for four consecutive months, and the CD32 version peaked as the second-best-selling game for the console, also behind Worms. According to Martyn Brown, by February 1996, the game sold 11,000–12,000 copies, with 15 per cent being for the CD32.

Alien Breed 3D was released to generally favourable reviews. Reviewers widely compared its gameplay to Doom, with some calling it the best Doom clone for Amiga. One such reviewer was for GamePro, who praised the level design and their inclusion of stairs and lifts, but found the graphics to be pixelated sometimes, while noting that the game is best played with a graphics accelerator. Amiga Format called it one of the best Amiga games of all time, praising the frantic gameplay and writing that it underscores the potential of the Amiga 1200. The One lauded the monster design and the combination of graphics and sound effects to create a frightening atmosphere, stating, "It is the best of the Doom clones on the Amiga A1200 by far, and is far more like Doom than any of the others."

Soon after the game's release, Clitheroe resumed work as the programmer for a sequel, Alien Breed 3D II: The Killing Grounds. It was released in July 1996.

Retro Gamer described how Alien Breed 3D inspired other developers to attempt their own Doom clone for the Amiga, including Breathless and Genetic Species, which benefitted from third-party peripherals such as external CD-ROM drives and expansion cards with additional RAM and more powerful processors that were retailed until around 1998, despite Commodore International's 1994 demise. The expansion cards were so powerful that the Amiga saw the release of a faithful conversion of Quake.