Think Minecraft, but crushed down into 2 dimensions. You're still not even close to what Terraria is. It may not be quite as creative as minecraft, but it does have the bonus of just about every magical weapon you can get your hands on, and a very well designed NPC system. Also, in this game mining is a sheer joy You are only guided by glowing plants in the unlit caverns and the glint of a helmet from an undead miner, but the caverns you can find. my God!. It may be influcenced by minecraft, but I think minecraft is beginning to be influenced by it too. (think of the nether fortesses compared to the hell layer cities in terraria). The expanse of the world is stunning. although it may be a world of limited size, the carverns below are diverse enought to enourage you to spend your life exploring every last one of them. And then there are the floating islands, jungles, dungeons and bosses. In a creative sandbox game. god damn fricking bosses :D

Goodbye social life, hello terraria!