We can arenas in mushu,aikido,judo etc, the white space is so boring.

We do this already through environments provided by modteam each month in public servers

@Fini; A lil tweak is in the options menu, its called "Shaders" completely changes all the colors. Find one you fancy.

try atmospheres. dunno if they still work tho

arena for mushu is just boxshu (exactly the same as mushu but with a box).
could also check the mods list for arena/box styles for judo, aikido and the rest.

Modteam literally makes environments based off each months theme to fill the white space and if they believed there wasnt a good portion of toaster users they would autoload atmospheres but for FPS sake they try to do the best they can with modmaker