Feature Killer

Say you're making a platformer. Features/mechanics would be something like: "You can jump", "You can run" and "You die if you touch a spike".

Now, add all these features to the list. 

Kill one.

What does your game look like now? What if you can't jump? How are you going to fix this? Is there another mechanic you could come up with? Is it a more interesting game now? 

Kill another feature, or make up a new one and add it to the list. Try different combinations.

This tool is super useful for brainstorming, but it also works well when you're absolutely stuck on a design and don't know where to go from there. When you're in this situation, it might be time to kill one of your darlings and see where the design can go from there.

Inspired by Alvaro Salvagno's article.