Superhero.io is the best IO game right now. Your goal is to move fast and collect as many golden orbs to grow quickly.
To survive long, you need to grow strong enough. Stay away from big enemies, and don't attack when you're not strong enough.
Right-click to move and dodge attacks. The game has up to 30 famous superheroes, upgrades, and bonuses. Complete levels to get rewards. Each bonus will help you improve your chances of survival, attack range, or movement speed. The game provides documentation for using Heroes. There is a life token.