UrT GOSU Mod. An official mod for Urban Terror 3.7 that increases damage, makes helmet shots knock the helmet off (so next headshot is guaranteed death), 
and removed movement penalty on the SR8 (for most of UrT history, SR8 had no movement penalty, so it was just a railgun; MP was added in 3.5 I think). 
Basically a promod for UrT. Was never played in competition, but it was designed to appeal to higher skilled players. 
Was pretty popular until 4.0 came out. I belive it was released to tide people over during the long delay between 3.7 and 4.0. 

Note: Requires Quake 3 and Urban Terror 3.7. Put the zzzSidGosu7.pk3 file in the q3ut3 folder.