Newly famous among the Doom community for its mind-bending map (including a terrifying hallway that takes six-and-a-half-minutes to get through), the innocently-named MyHouse.wad is certainly the Doom mod of the year. It immediately earned itself a spot on the all-timer list back in March, in spite of the game's long modding history.
MyHouse.wad is a surreal, enthralling narrative, and my first encounter with it took place via a feature-length long video essay that gnawed its way through my entire afternoon. I'd recommend you play it yourself, however, as it's far more fascinating to delve into firsthand. A close second would be watching the creator of Doom try it for himself.