This has to be one of the weirdest/irrelevant game series' out there, along with Sniper Ghost Warrior. I've never personally played any of them aside from ZAT, which I didnt like at all, but none of them even looked remotely good. I cant imagine they've sold enough to warrant 5 (or more?) games in a series with any other company.
-2/10 on the trolling, I'd suggest trying the PSN thread instead