If you're a fan of sci-fi games and Minecraft, check out Block Fortress: Empires. Here, you'll get to choose to live on six different planets: radioactive, volcanic, tropical, frozen, Earth-like, and desolate. On these planets, you can build houses, add decorations, and use teleporters. Be careful of enemy players, though, because they will attack your home when you least expect it. 

To fortify your humble abode, you need to deploy soldiers, turrets, and traps. Alternatively, you can raid other players' bases and show them what you're made of. Exercise caution and employ tactics that will give you the upper hand. On the bright side, you can also forge an alliance with friends to build the empire of your dreams.