Based on Robotron: 2084, players of Llamatron control the eponymous creature in an attempt to stop an alien invasion of Earth and rescue animals—referred to as "Beasties"—for points.

As of March 1992, at least 800 people had registered the game, making it unusually successful for shareware distributed without locked features or other purchase incentives.

Reviews of both the Atari ST and Amiga versions praised its addictive gameplay, sound effects, and value for the registration price.

"Grunts" take a variety of forms, including Coca-Cola cans, kitchen utensils, cherries, Space Invaders, Eyes of Providence, televisions, fire hydrants, Zippy the Pinhead, marijuana plants, and Rizla rolling papers.

[2][4][5][6] Other enemies include indestructible devices that shoot screen-wide lasers, 16-ton weights that attempt to crush the player, hedgehogs that explode into spikes when destroyed, Mandelbrot sets that shoot projectiles and scream when hit, and a large toilet that throws rolls of toilet paper at the player.

At the time of its release for Amiga computers, people who registered would receive another game from Llamasoft, a poster, and a newsletter.

"[2] Amiga Format reviewed the game in their September 1991 issue, giving it a score of 89% and highlighting its "simple gameplay [that] is fast and massively addictive.

"[1] The review did mention several sound and graphical glitches, as well as occasional problems with collision detection, but overall recommended it as having "superb value".

Writing for ST News, Richard Karsmakers called the game "brilliant" for its "sheer playability, playing fun and other things that really count.

[6] A retroactive review of the Amiga ST version by The Inquirer in March 2007 said that Llamatron "without any question [...] is, was, and will always be a great game.

"[11] His success was seen as unusual in the shareware market and due in large part to the fact that Amiga Computing featured Llamatron as its cover disk.