current test maps was also used for russian tournament with random maps
and organiser asked specailly set all maps forest
check maps pud files they just all forest and game mode just making map def tileset
yes you can put your own maps in folder after you join server and u can even play with comps
but u wont be able to play with other player unless they have exact same maps in folder otherwise dessync and drop
BUT even then even if u play some other maps they DO NOT count to ladder games becoz there is also other check on server itself for exact maps to be played to count for ladder so not worry