The characters are human beings wearing Powered Armor that resembles stickmen
The characters are all wearing space exploration suits on their mission to save their home dimension from badness. They are actually looking out of the 'mouth' of the suit, and the 'eyes' of the suit are actually lights. How about it?
  • Interesting idea, but how the crew would they express themselves with their supposed 'mouths', unless they actually are mouths?
    • If Viridian were to become upset, he'd stare into the distance, and his head would be sort of angled down or up (the effect of which would be slightly magnified 'cause the helmet would be huge). I thought that the suit lights (the eyes) would be made to follow where the wearer looked (some kind of retina tracking thing). So, if he were to look down, the eye lights would angle down to follow his eyes. Voila! Viridian is sad: visible shape of eyes and mouth changes. :)
    • Whoever drew that 'Pac-Man as an astronaut' picture had the same idea apparently.
      • The remix CD (PPPPPPowerup!) has all of the crew members drawn with powered armor on, so this theory would appear to be confirmed.

Viridian is a Time Lord, explaining his constant regenerations.
Because SOMEONE had to say it.
  • When your companion asks what those 'C's are (the checkpoints that revive you), Viridian tells him to not question it and pretend they don't even exist.
  • In other words, the checkpoints are his TARDIS?
  • Then he would have rewound back in time to not be in the whole incident to begin with.