2K and Rockstar parent Take-Two Interactive has made a rather mysterious domain registration.
Take-Two registered HungoverX.com on July 25, according to Fusible.
The domain has been switched to Take-Two's name servers but doesn't go anywhere at present.
There's no evidence to suggest this is a new game or major project, unfortunately, especially as the publisher is known to be generous with its marketing budget when it comes to websites and AR games related to Grand Theft Auto. GTA 5 launches in September, so it's quite likely anything publicly accessible that Take-Two does for the next few months will be related to its juggernaut PC, PlayStation 3 and Xbox 360 launch.
Take-Two hasn't bothered to grab other domains related to the phrase "HungoverX" which lends weight to the theory that this isn't related to a new game announce.