Lots of students enjoy playing Minecraft, a game that uses blocks to break and build things. Fantastic structures, mysterious castles, and gathering and crafting items are a big part of the lure of the game for players. It's also a game that with your avatar you can fight off creatures of the night and build your world as you'd like it. It's not as violent as many multi-player adventure games, though it involves some killing of creatures (no blood, just a grunting noise indicating that they have died).
For more on Minecraft read these couple of reviews - one from and avid and creative player Anthony Gallegos and one from a mother, Bec Oakley, of MineMum who appreciates and elaborates on the learning benefits of the game, and has put together a site that helps other parents understand the game better. She gives a thorough overview of Minecraft including how to install the mods/modifications that help enhance the game.
I need to spend some more time on Minecraft myself, as some teachers are finding it quite educational and helpful in their classes as a way to teach all kinds of curriculum from history to microbiology. Check out Minecraft EDU for further info on that.
Recently, ThoughtSTEM, (think Science, Technology, Engineering and Math), came out with LearntoMod.
Through this mod making program students create their own mods, and the great thing is, they are learning to program while they create. Learning programming is big, and if your students are enjoying what they are creating through their programming sessions, all the better!
Check out this recent article in Wired for further info on LearntoMod.