Alien for the 2600 was the first video game based on the Alien film franchise, which now has over 30 games for various platforms. It was developed and published by Fox Video Games.
The gameplay is similar to Pac Man; you control a blue person (presumable Ripley) and run through a maze, collecting dots. The goal is to collect all the dots, and by doing so, complete the stage. There are teleport spots on each side of the maze which can be used to move the player from one edge of the maze to the other.
Three aliens chase you around the maze and you lose a life if you come into contact with any of them, unless you grab the large orange dot which is always located at one corner of the map. If you do so, the Aliens turn blue for a short time and touching them in this state will return them temporarily to their home base. There is only one orange dot on the screen at a time, but collecting it will cause it to reappear in another corner of the map shortly afterwards. The player also has a flame thrower that can be used to defeat the aliens.
The bonus stage in between each level is very similar to Frogger. It is a stage in which lines of enemies are moving from left to right and the player must travel upwards through gaps in the lines in order to collect items. If the player is touched by an alien, the bonus game ends and you will start the following level of the game.
The difficulty switch on the 2600 changes the speed of the aliens and the amount of lives the player begins with.