Alien Gate is a fixed shooter developed by SPC Vision and published by Philips for the CD-i.

The background gives the impression of a vertically scrolling shooter, but the attackers stay in position relative to the player's ship.

[2][3] The code and graphics were all written using the Atari ST.[4] The project began as a demo provided to publisher Philips who were so impressed that they commissioned a full release as well as a five-game contract with the developer.

Alien Gate was put together during that six week period and Moss was asked to return for a permanent position.

Posthuma subsequently took a job at the Canadian developer Gray Matter while Moss returned to England to work for Argonaut Games.