Have a look at Unity's Prototype series. It was created by the Unity Evangelism team to explain the creation of playable prototypes. The team broke down multiple features of Unity that can be used to set up game mechanics for different real-world projects.
The team plans to release a new episode of the series each month: a video explaining how the mechanics were created, the project assets, plus supporting tutorials to learn more about the features. The first one is dedicated to creating an ability system.
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