Terraria by RE-Logic
Terraria is a 2D version of Minecraft. Players can virtually do anything they want in Terraria, whether it may be making weapons to fight off enemies, develop tools to dig deep underground or scavenge to find accessories, money, etc. Players can also harvest resources such as wood, ores, stone and so one to build new tools and upgrade old ones.
As you find stronger resources, you can go from building a house, to building a fort to building a castle. However, as you get stronger both good and bad things may begin to happen. Although people will be more willing to trade with you, enemies will get jealous and begin to ambush you. Everything you build must be protected. Beware, the more you explore, the more challenges you will find.