Fungus is notable for being developed when Hörnell was still in high school, during which time he learned machine code to create his own Commodore 64 games, also handling the artwork himself.

It was positively received by critics, who cited its graphics as impressive, and praised its gameplay, considering it above-average for a budget title.

While one of the viewers described it as "rather frustrating to play at first", he soon found it "compulsive" and "addictive", summing it up as a "pleasant game in every way".

[2] Laurie Simpson of Commodore User magazine also gave the game a high rating, calling it "light-hearted" with a "professional polish".

[1] Hörnell spent subsequent years developing Fungus 2, an improved sequel in every respect, which he considered his magnum opus.