That may be but we never saw it. I always felt Atlantis was a really worthy new entry into the SG franchise. Also, given the lack of proper ending, it would provide the game with that much more creative freedom.
Imagine a trilogy for SG:A where the final solution to wraith culling is the premise. What wouldn't I give to see a digital version Rodney Mckay (and he is Canadian) voiced by the living one. I also liked Joe Flanigan as Sheppard (Wrex.. Sheppard... Wrex) and rest of the protagonists. Imagine them rendered in close to fidelity (multiple orgasms, why doth thou blessed only women with thy self?).
Personally, a game like that would benefit greatly from being story driven and integrating a dialogue system like that of Alpha Protocol (timed) or ME with third person mechanics. In the hands of talented developers it could become a true masterpiece. Lest we forget, the franchise already possesses a strong brand recognition.
I was talking more to your sg1 point about the finale, but I agree with you to the extent that I want an SG1/A game that is something like you mention though with greater squad control (like a rainbow6 or SWAT title)