Honestly, if you have enough friends in the game, have them make an appeal to the owners of the game to let you continue as a GM. Other than that, unless this has harmed you in some way, there isn't much you can do (under these current facts). What is it that they think you did?
The above is not intended to be legal advice, but may be used for general information. Please contact an attorney for specific help tailored to your needs. www.figgardenlaw.com
I've been in the games industry a long time and have heard this type of situation come up several times in small independent games (MUDs and web games especially). Usually there's nothing you can do. Since you mentioned that you invested in it, do you mean that you have spent dollars on the game or did you actually sign a contract entitling you to some value in the studio (which would be the relevant kind of "investing" here)? We'd need to know things like this in order to answer your question completely, but frankly it doesn't sound like you've got much to go on here.
The author is a Maryland attorney; however no answer given on Avvo is intended as legal advice or intended to create an attorney-client relationship. Dan's expertise lies in the electronic entertainment (video game) industry, as well as complex internet law issues, electronic free speech, entertainment law, copyright and trademark law, and computer fraud. He primarily represents game developers and founders of emergent internet technologies.