Terraria

Terraria is a deep exploration and building game. You move around a side-view 2D environment, both on the surface and below ground. You build your home and create objects from raw materials. You can even build a town. The graphics are retro pixel images that sometimes make it hard to see what is happening, and the controls are far from perfect. But this game is worth every penny as it looks like you can play for days, months or even years.