Slither.io is described as 'Slither is an online multiplayer game that meshes concepts from both Snake and Agar.io. Play against other people online!'. There are more than 50 games similar to Slither.io for a variety of platforms, including the Web, Android, iPhone, iPad and Android Tablet. The best alternative is Agar.io, which is free. Other Slither.io like games are Diep.io (Free), Osmos (Paid), Wormate.io (Free) and Agar.io Clone (Free, Open Source).