- a tremendous learning experience
- a resume booster
- easily accessible
Personal example: I never wanted to be a game developer, but I was interested in how games work and how to make them better feature-wise. After looking around I found the Xonotic project, for which I now provide feedback and test for. It's a win/win for me and the project team; I've learned a lot in the process and the project team gets free map reviews and gameplay videos.