My friend linked me to the steam page for
Tactical Breach Wizards, an in-development turn-based tactics game from the Heat Signature devs. It looks pretty cool, but what impressed me was the demonstration of one of the character's mechanics. The witch is described as a "by the books" officer, and that's reflected in gameplay by her gaining mana for only using necessary force. Essentially you should aim to kill an enemy by dealing exactly the amount of damage needed to deplete their health, but no more. To me that sounds like a really neat mechanic that also ties in nicely to her characterisation.
If I were to answer the question from a game I've recently played it would have to be Katamari Damacy Reroll and the way it disguises the loading between different sized environments as you grow bigger. It's really seamless and allows for such stupid escalation, especially in the latter levels.
What's a recent neat mechanic that you've come across?