Battlefields.io is a free-to-play online multiplayer game about strategy. You enter the game facing off against three opponents in different parts of the map. You each start out with one tower with the maximum amount of units. Play the game by attacking neutral towers to gain an advantage over your opponents to take all of their towers. The last player remaining wins the game! It's that simple. However, there is also a large amount of room for strategy. Every level you earn has skill points that can be used to upgrade attack, defence, speed, and reproduction rate.

Golf Royale is a realtime minigolf game where you can play against up to 50 opponents at once! You will race to complete each course more efficiently and in less time than your adversaries.

Fully physics driven and 3D, you will need to some quick reflexes and skillful maneuvering to navigate the dangers of the more challenging levels the game has to offer. Use your skills to make shots while your moving at high speed, bounce around obstacles and traps, and sling the ball all around the golf course.

Nullstar.io is a free 2-D shooter game. In this exciting game, you combine the addicting and powerful worlds of slither with asteroids. This is a simple and fun top-down shooter game that combines the best elements of all free arena games. This is a top-down shooter game in 2-D where you are the pilot of a spaceship who has to avoid asteroids and other pilots who are armed to the teeth with laser-powered weapons and are absolutely on the hunt for a pilot like you to take down and destroy. Blow up asteroids to gain resources.

Worms.lol is a free slither-style iogame. This game aims to be one of the most popular .io games. In Worms.lol you can complete challenges to get rewards like hats, different mouths, eyes or glasses. When you start the game you spawn as a little worm and you have to eat mass to grow and become the first in the leaderboard. The good part of this game is that you can defeat the BIG worms even being a little one. All you need to try is to make their head hit your body. The point of Worms.lol is trying to become number one in the leaderboard.

HOW TO PLAY WORMS.LOL

Evonite.fun is a free evolution style game.

Cut down trees and palms, bushes and cacti to grow in size while you are small.

Attack smaller enemies, so you have a better chance of staying alive. 

You can save yourself just run away from large enemies so that they do not kill you with one fell swoop of their powerful weapon or you can donate your experience to the enemy. But you won’t be able to run for a long time, because when you run, your experience decreases.

The game has only 12 levels:

Hury.io is a free chicken-style game. Collect eggs, attack other birds!

Become the biggest, crowd bird!

3 Game Modes:

1- io Mod : classic io gameplay

2- Battle Royale Mod : be the only winner

3- Team Mod : win with your team

Gameplay:

Click the screen anywhere and drag with your mouse.

Speed up with "space key".

Attack other birds with "right mouse button".

Bladez.io is a free survivaal style io game. New survive io game! You're in a wide field, you have a small blade in your hand, and other people are attacking you, protect yourself, and try to hit the others head, if you do that, the bladez in your hand will grow. It's time to demonstrate your speed and power in the game "bladez.io". In this multiplayer io game, you cross swords with players from all over the world. Before entering the arena you need to enter your nickname and choose a skin for the future winner. Your hero will be a fast and agile warrior who perfectly controls the sword.

Slither.space is a cute anime inspired slither style game. Slither.space cool if you don't because these snakes are no threat to you. Other players, on the other hand... Enjoy a twist on an old classic with slither space! Like the classic game Snake that was available on cell phones and computers for decades, you grow by eating small pellets. But with its multiplayer gameplay, you now get the same action while competing against other people. Feel free to chow down on your smaller enemies, but remember that there's always a bigger snake who can kill you!

EvoWarriors.fun is a free 2D fantasy game.

Eat steaks, eggs, milk and everything you find to grow in size while you are small, most importantly do not eat amanita, because it reduces your experience and you become smaller!

Attack smaller enemies, so you have a better chance of staying alive. 

You can insure yourself just run away from large enemies so that they do not kill you with one fell swoop of their powerful weapon or you can donate your experience to the enemy. But you won’t be able to run for a long time, because when you run, your experience decreases.

Polygun.io is a free 2D top-down shooter game. In this retro-inspired game, you'll use geometric tanks that evolve with your experience to become faster, more powerful, and excruciatingly deadly. This is a game of reflexes, strategy, and luck as you grind your way through an arena filled with polygons. Some of which are enemies that fight back and some of which are simply there to provide you with a nominal percentage of experience points which you can save up to eventually buy upgrades.