[Solved] Coincidentally I came across it while reading an unrelated thread about Ghost Recon on X-Box: it's Ground Branch.

I know I just saw the other day a game in development, whose team members included people that worked on the original two Rainbow Six games for Red Storm - but I cannot remember the name of it. I tried to Google it but there are just too many wrong results coming up for me to find it. The game was supposed to be in the same vein as Rainbow Six.