Details for Undertow are located here. It looks like a decent game and it is free so I figured why not try it out. Well I'm not going to play it yet but I'm downloading it while it is still free.
It says 2:00 a.m. but I was able to download it right now which was around 12:54 so go out and get it while you still can.From the link above wrote:Regularly 800 points, Undertow is free of charge beginning 2:00 a.m. PST Wednesday, January 23 and continuing through 11:59 p.m. PST Sunday, January 27.
Also before anyone says "WTF I already downloaded this when it wasn't free" my answer to that is this.
From [url=http://www.xbox360achievements.org/news/news.php?id=644]x360a[/url] wrote: If you already have it, you should be able to contact Xbox Live support and they are supposed to "take care of you," though some people have claimed support told them this version of Undertow is different and they won't be offered a different game... I think they just got a bad employee, so try again if you get that response.