1. Create a new filled map (RightClick on empty map)
2. Read map id
3. Use /mm<gamemode> play <mapid>
3. Stop using /mm<gamemode> stop

Test:
/mmtest help
/mmtest play <mapid>
/mmtest stop
/mmtest highscores (currently no use for that)

Snake:
/mmsnake help
/mmsnake play <mapid>
/mmsnake stop
/mmnsnake highscores
Controls:
Up: Jump
Down: Sneak
Left: LeftClick
Right: RightClick

Tetris:
/mmtest help
/mmtest play <mapid>
/mmtest stop
/mmtest highscores
Controls:
Move piece: Left and Right click
DropDown piece: Sneak
Rotate piece: Jump