To check out the map, simply paste the bsp in "Team Fortress 2\tf\maps",
then run "sv_cheats 1" and "noclip" in the in-game console.
To play it as intended install the MGEMOD plugin (https://github.com/sapphonie/MGEMod/tree/master)
and simply paste mgemod_spawns.cfg contents into an identical file there.
mgemod_spawns.cfg is useless otherwise.
To see how it plays you can also check it out on castaway.tf virginia 2 server: 
40.160.50.187:27015 or va2.castaway.tf
Or other castaway.tf servers in the future.

Changelog:

mge_castaway_v1b

- Added 2 new arenas: Poolday and a secret one. Poolday is accessible from 2000+ ELO points,
while the other from 9999+;
- Fixed custom decals z-fighting (such as on turris and bball);
- Various minor visual improvements to the skybox and around arenas;
- Adjusted spectator/welcome screen decals;
- Compressed map's file size significantly.
