www.creeptd.com

Possibly not what you’re looking for, but Terraria has a Dungeon Defenders-like sidequest you can do, which I think is available in multiplayer. It is kind of fun, but not too challenging if you already have endgame gear.

if u have discord, minion masters is a tower defence game where u build a deck of cards and u pick these cards when u have enough power to use them and it places a monster on the battlefield to ru ntowards the enemys tower and damage it. very fun game and its free 2 play

Somebody that has apparently made their first post today, necro-ing a thread started by somebody that has apparently only ever made a single post two years ago... Just making an observation, since I've added my input two years ago.

well it's only two but... Gorillas,
you know that game where your put in trajectory and speed and your towering gorilla throws their bannanna at the other gorilla tower hoping to score a hit lol :P