or as i like to call it,
very simplistic and easy to learn mmo browser games
iogames.space - a big list of games. if anything, you should check here first other than scroll through this. but if you want, go ahead and look here.
agar.io - the beginning of it all. move around as a small circle eating other smaller circles and running away from bigger ones. the most well known and the oldest.
slither.io - a pretty recent game. similar to the game snake (that really old game) but a lot more freeform. eat the various glowy food. don't run into other snakes, but let others run into you to steal their length!
wings.io - fast paced airplane/jet fighting with guns, rockets, and other things. kill others and get a lot of score.
diep.io - the slower paced version of wings.io but with a lot of other stuff. upgrades, classes, and a lot of other stuff available. shoot circles and shoot other shapes to increase your level and score to upgrade yourself and get a better class.
cursors.io - cooperative cursor madness. solve puzzles with multiple people, and screw other people over by escaping first. in a way.
vertix.io - 3v3/6 player shoot em' up vs game. multiple classes to choose from and hats. like TF2 but topdown in a way. kill people with gunz in different game modes.
vanar.io - like asteroids, fly around, destroy asteroids and other players. shield to protect from incoming shots and don't run into things.
voar.io - what REALLY started it all. deceased, and you can't play it anymore. made by same guy who made agar.io. explanation:
Actually voar.io, another game by the same guy who made agar.io, was one of the first .io games. It was a gravity-survival simulator thing where you launched a rocket from Earth and tried to see how long you could stay in orbit while trying not to crash into other players (and then sometimes the moon or an asteroid would show up and forget everyone up). Unfortunately, voar.io is dead right now and while Zeach (the creator of agar.io and this) said he'll eventually bring it back, it still hasn't been done.
agar.pro - some different kind of agar? i didn't see much, but play it i guess
wilds.io - it's some kind of medieval fighting thing. i didn't play it too long, but it looks fun. give it a try, maybe.
if i missed a game/there's something i didn't catch, let me know so i can toss it up here and also give it a try maybe.
diep.io is so fun omg, and as long as you stay away you won't find much people but shoot a lot of things and level up pretty fast. sniper's fun af