I came up with a central mechanic!
Basically, there shall be two versions of each level which you can switch between at will. One, the happy adventure, will involve no risk, and you can waltz right through without being troubled. Enemies will be friendly, and act as lifts and elevators and the like. You gain no score for this.
In the sad journey, you gain score by the bucketload, but are absolutely swarmed by enemies. Perhaps there will be different ways to go through the level depending on which version you are playing, I dunno. Anyway, the basic idea is a risk/reward approach to score, with that being controlled by the player. It could be fun or, you know, not fun.
There will be a different story depending on whether you are in the happy or sad, which will hopefully give you more reason to switch between them. I suppose that really depends on how well I can write about a rabbit.
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So, ehm, I think I broke my game:
Whoops.It's pretty hilarious, but I should probably fix that.
EDIT: Fix'd.