Should I let my fans keep making a fan game?

[ShiroKansen]

I mean technically it's illegal since no licensing but what happens if I let them be or do something against them?

[contrabored]

If you let them, you earn fans.

If you sue them, you'll get some money - but lose fans.

Overall, I don't think it matters long term. If your fairly early into the game, I would advise letting them use it because from my own experience, I've never got that much money from taking action, but always lost a hefty number of fans.