Sean Howard, a veteran game designer and developer, has imposed himself a challenge to write up one gameplay idea that hasn’t been implemented yet each day for three hundred days.
There are some pretty nifty ideas in there, whether or not they have already made it into a game, and some of them are really qualified for a roguelike (idea 004, for example has been used in some roguelike games with procedurally generated quests). The author is cool about people using these ideas in games, so you can feel free to grab them and use it in your roguelike.
Also, his pixel art is cool 🙂
Further info Here