Basic Legal Question


I have just made a module of a game that is owned by a friend in Vietnam. I offered to make the module for him so he could spread his game and so that players could by internet and email.

My friend now wants to use the vassal module to host tournaments, possibly with prizes and the like. I just wanted to be absolutely sure that there were no legal issues I was not aware of in using the vassal engine for tournaments and such. Could somebody please advice me?