Move or Die [Steam] might be my favourite party game, it's absolutely nuts, it can be played with by yourself and with others locally and online. It just had a big content update too.
They've add an in-game store, which features all the characters, mutators, items and so on. Usually, you would unlock stuff at random as you played it, now you don't have to wait. You will still unlock stuff, but you can also buy items using "NOT-COINS" you earn from playing it, they're essentially poking fun at micro-transactions and I approve of this.
They also added 7 new characters, 7 new mutators, 4 new game modes and you can now enable mods in private online lobbies now too, for that extra bit of fun.
Check out the ridiculous trailer they made for the update: