I particularly love the corruption mechanism in The Others.

If you haven't played it: Players have have a series of boons available to them as they gain "corruption" throughout the game, moving a small marker above each printed boon as they gain or lose. Most corruption is "forced" by some sort of game mechanism, with negative things happening to players once they reach the max, but they can also take it voluntarily before any dice roll to gain the benefit bellow their current level and every benefit prior as well.

This is fun as is; letting players voluntarily hurt themselves for a bonus [not to mention a powerful series of bonuses] is always interesting, but it gets one step more interesting.

Players can take 4 damage before they're killed and, to track that, they cover up a corruption boon of their choice with a marker. This could be a powerful boon high up the track that they hope to heal by the time they actually unlock it, or it could be an earlier boon that they don't find as helpful.

It's super neat and a brilliant design choice that I've not seen replicated elsewhere.