What is this map?

Fight 20 waves of difficult underwater monsters that vary with each round! Unlock better gear, amazing powerups, and incredible traps. Or, if you aren't really ready to play the minigame yet, enjoy the archery minigame in the lobby! This is an entirely replayable game that you can enjoy by yourself or with friends.

Other info:

1. Map built almost entirely by hand by asluup: follow him on twitter, @asluupp. All commands done by PvPqnda; follow him on his twitter @PvPqnda!
2. This map may take a long time to complete, so take as long as you need! After each round, you're given an indefinite amount of time to rest your brains from the amount of crazy fun that you're (probably) having.
3. It's really interesting that there's such a decorated landscape, but you can't get up there, isn't it? Or can you... I feel like there might be something in the lobby...