Guncraft is a first-person shooter stylised much like Minecraft and its boxy facade. It's a multiplayer game whose players create the customisable maps, and can fully mod the game to their heart's desires. The PC game is currently in open beta, which you can sign up for, or help get on Steam.
One of said maps available to play on in the beta is what you see above. The best thing about the Empire Strikes Back map is that the AT-ATs are fully destructible, as well as anything else on that or any other map.
As a bonus, here's a Minecrafty map in an actual Call of Duty game -- Black Ops -- where you can go on a piggie murder spree.