Certain video games have patents on certain topics and game features, like dialog wheels.
A patent needs three things: The invention must be new. The invention must be useful. The invention must be non-obvious.
Seems like many games might wish to use this for specific features. As for Better Games, the twenty year limit on patents would make Ignobles or flip card missions or Digression tables and Q&D, already expired.
As for DnD, never thought there was a roll D20 patent, nor could there be, since rolling a die is obvious in a game. Yet Gygax's XP and HP systems? Well, long past expiration of concept as well.
Are there any new game mechanics in adventure games?
Let me know. I don't buy games; I just don't. Be nice to think something original is out there that would meet the three conditions for Patent.
Hysteria making characters change class (in Demon Hunter series) may qualify. Not sure I know of any game that has that concept, forcing a character change from poor execution of actions. But then, I'm a genius at game design. Ass at marketing and art direction, but gifted at play design.