A 2-D Side scrolling sandbox survival game with a focus on adventure and bosses. Terraria is a great game for anyone looking for a good platformer.
One of the most popular games in the world League of Legends is a MOBA where two teams of five fight to take the others base.
The sequel to borderlands, borderlands 2 is a first person shoot and loot game focused around improving your gear and moving through areas to get to the ultimate goal of opening a vault.
Path of Exile is a third person action role playing game. Your character awakens on a beach having been exiled with one goal in mind, survive.
Runescape is one of the oldest MMORPGs around, you start on a tutorial island and adventure around gielinor in search of fame and glory.