Discussion and Community testing initiative dump.
The game's a year old, and there's no thread about P2? Well it's an awesome game if you haven't had the chance to play it.
It has at least twice the story mode value of the first game, along with a multiplayer option. They also recently added a workshop, so that you can make and play custom maps with ease.
The custom maps, at first, didn't interest me. I thought I'd make a few and be done with it, but when you play a custom map, you get a nice little nugget of new Cave Johnson dialog. I'm kinda hooked.
Also, here's my dump of the (currently) 2 maps I have made and published:
http://steamcommunity.com/id/Wrrrtw/myworkshopfiles/