Project Velocity (aka Octane) is a cancelled racing game that was in development by Visual Science for the original Xbox (and maybe for the Playstation 2?). It seems that this prototype would have been a new title in the Need for Speed series, but there are not many info about it.
As we can read at Past to Present:
Way back in 2007, Gamerfreak1727 leaked a title he found on a debug Xbox called ‘Project Velocity.’It seems to be an early version of one of the Need for Speed Underground games, with references to the ‘Underground’ race style. The issue being, the build date seems to be around January 20th, 2006, almost a full year after Need for Speed Underground 2. It is possible that it is a prototype for an unreleased sequel, or even one of the other spinoffs like Need for Speed Carbon, but I am not 100% certain where it would fall. Any NFS fans who want to chime in, feel free!