Masive update:

GameServer.objects(ip=ip).update(set__status=Server_status.STATUS_RUNNING)

You can use the double underscore:

Tournament.objects.filter(type__num_players=2)

Or raw queries:

Tournament.objects.filter(__raw__={'type.num_players': 2})
TournamentConfig.objects.filter(__raw__={'$where': 'this.type.num_players * this.type.num_teams == 4'})