So I’ll finally write about this. I created a mode back in Halo 3 called Halo Football aka Blood Bawl. I published it to Bungie’s servers on October 7, 2007. You can see the file here: http://halo.bungie.net/Online/Halo3UserContentDetails.aspx?h3fileid=4199932.
Couple people played it. 279 downloads. 64% rating. Not too bad.
It was basically Grifball before there was Grifball. Grifball was created on or around December 16th, 2007.