This game works because it merges three compelling genres into a package that works.
1. Digital Legos. Who DOESN'T like Legos? The problem with physical Legos are myriad... you need approximately &750,000 to amass the amount and variety of blocks to do anything epic, the inevitable mess rivals a post apocalyptic wasteland - which also causes serious foot injuries, irreparable damage to vacuum cleaners, and present a choking hazard since they look like candy, and candy is delicious. Minecraft gets around all of these issues by presenting an infinite virtual world that cannot be swallowed or stepped upon. Carpal tunnel is still a danger.
2. Zombie Apocalypse Survival Horror (With special guests: Pickle Jihad Battalion and Werewolf Spiders that are only angry at night) - With physical Legos, you only had to worry about that sociopath rescue dog your sister HAD TO HAVE coming by and om nom noming your scale replica of the HMS Ark Royal because he's already chewed every single power cable in the house into sopping masses of PVC and copper confetti, or that bastard little brother who knows he has diplomatic immunity and exploits this with wanton glee as he dismantles hours of work. In MINECRAFT, there are approximately 3 reinforced battalions of Zombies (whose diets consist of chickens or feather pillows, apparently), Skeletons (who, thankfully, rival Stormtroopers and gang bangers for inaccuracy), Spiders (approximately the size of minvans or small SUVs, climb walls, and whose diets consist mainly of YOU.), and FINALLY, the legions of Pickles (Officially known as "Creepers") - Basically, a pickle and a tactical nuclear device got drunk and these were the result. They are quiet, and just want to be close to you. They are very excited. Which is why, once they get close to you, they detonate. Usually this happens when you are building a plate glass window on the side of a cliff... the result is the cliff is now a crater in the hillside, and you are face planted on the stone below, all your painstakingly accumulated worldly goods strewn about in a macabre crime scene portrait. Your items will persist for some time, though! This time is calculated as follows: X - 5 seconds. X being the amount of time it will take you to run back to collect them (in the unlikely event that you: A. Can find your way back to where you were, and B. You don't die 14 times on the way.)
3. Nerdo-Masochism - The subliminally devious sites and sounds work their way into your sub-conscious, stimulating the same pleasure centers as heroin, deep fried desserts, and celebrity divorce battles. You will become the computer science equivalent of the SAS, as you battle to make the game run properly, only to have a forced update destroy everything so you can start from scratch. You will gleefully punish yourself for hours, digging fake holes in a fake world while running from Pickles, falling to your death, burning alive as you tunnel into lava pools roughly the size of the Indian Ocean (approximately once every 17 minutes). Why? Because you have other nerds to impress with your fake dollhouses, and zOMG DIAMONDS!!!! (Which you will decide to take back to your vault for safe keeping approximately 14 seconds before the Pickle Jihad triangulates your sub-dermal homing device and blasts you into a lake of lava roughly the size of the Indian Ocean).
To summarize, possibly the best game ever created.