We (http://pr0gramm.com) had a multiplayer battleship[1] for our april's fools two days ago. All users were divided into a red and blue team and then voted for the next shot. For our april's fools in 2018 we did the same with connect 4[2].
The games itself are not that interesting (altough OP certainly disagrees), but the social dynamics, shitposts and memes that came out of this were fascinating.