One version is common, at least one other version is rare
 Game design by John Dale and Martin Day; level design by John Dale. Coding by John Dale and Adrian Stephens. Graphics by Adrian Stephens; graphic design of monsters by Herman Serrano. Sound by John Dale and Martin Day (Spiny Norman).
 Levels 61-70 are broken in the game - when you get to level 61, it will automatically jump to the next level until it reaches level 71. Additionally, the last ten levels (71-80) have to be played in two-player mode by default as the screen is newly-split into two halves.