3. League of Legends
Like DOTA 2, which is up next on this list, League of Legends is a MOBA, or multiplayer online battle arena, where players choose their heroes to do battle on a field where two sides compete for dominance. Impressively, League of Legends is the most popular online game right now due to its low barrier for entry and the fact that it's free to play. Players can purchase aesthetics to customize their favorite heroes to show off in battle.