- or if you have multiple maps: a lizard would start on let's say a swamp like map and a dward in some dwarf mine like map.
No, all players must be on the same map.
I wonder if by 'map' he strictly means 'level' in DOS terms or if he could be satisfied with different terrains on the same level, which may be good enough for his purposes?
That's true, you can have multiple independent "maps" in the same level, and it's no problem if different players are in different such maps (to the engine, it's just different coordinates in the same level).