Yes, I understand, but it may allow you to use the code on Steam. I maybe wrong though.
It unfortunately does not. I redeemed it on ubisoft's uplay. It took loving forever though, for at least a week and a half the ubisoft shop website was completely loving broken and wouldn't even let me checkout AC3 to use the promo code.
I don't know why Nvidia would even bother with any non-steam free game. Really it's absolutely useless. At least it wasn't a "7 hour trial of SC2".