gamemodes_server.txt

"mapgroups"
	{
		"mg_bomb_se"	// mapgroup definition
		{
			"name"			"mg_bomb_se"
			"maps"
			{
				"de_dust_se"		""
				"de_dust2_se"		""
				"de_nuke_se"		""
				"de_train_se"		""
				"de_inferno_se"		""
				"de_aztec_se"		""
			}
		}

		"mg_zombieescape"   // mapgroup definition
                {
                        "name"                 "mg_zombieescape"
                        "maps"
                        {
                               "ze_echo_boatescape_go"  ""
                        }
                }
        }
}




Then in the Command line i have - +game_mode 0 +mapgroup mg_zombieescape +map ze_echo_boatescape_go