Glorious, glorious madness. You just gotta love mash ups that put two insane games like these together.
This mod recreates the dungeon layout of The Binding of Isaac in a TF2 map, including locked rooms and even some horrifying bosses. My favorite part has to be how the players go deeper into the "basement" in this mod, too.
It's impressive, and might be just the thing to tide you over before Team Meat's upcoming Binding of Isaac remake—which lets you play co-op. But I'm assuming that version of The Binding of Isaac won't include as many people as this TF2 mod... or, you know, stuff like guns. So this might be more preferable to some folks.
You can try the mod out here, if it happens to come into the map rotation. Judging by the other available maps, which feature Smash Bros and A Link To The Past themes, it won't be so heartbreaking if you have to wait a while till you get the Binding of Isaac map. Just an FYI.
Brilliant-Looking Mod Mashes Up TF2, Binding Of Isaac [Rock, Paper, Shotgun]