100th is a short but deep puzzle platformer with a fairly simple difficulty curve, plus optional and difficult challenge branches (for those who feel so inclined). It is not extremely difficult to complete, but there are a lot of secrets for those hardcore completionists out there.
In 100th, you play a small character with a balloon companion. There are no enemies, only environmental hazards; your fickle friend, however, makes for a uniquely challenging experience to the end.
Earn extra bonus points if you make it to the end with the original RED balloon. If you lose the balloon, you can always get a blue one, but this will result in fewer points.