The current gameType is limited to a few current options. If the players mission that is created does not fit into the provided categories then the gametype "Unknown" is the only option.
Possible sollution would be the addition of a "Misc" option, or an even better solution would be the ability for the play to be able to define his/her custom gameType as a string.
eg1)
gameType = MISC;
eg2)
gameType = "My Custom gameType";