Actually, if you're in a stealth mood, there are also very different genres that provide that kind of thrill. Just saying this because I love submarine simulators since "Silent Service" on the Amiga and "Aces of the Deep" on PC, and the hide-and-seek tension of these can't be topped. I also played a lot of "F-19" (basically the same game as "F-117"), which is the sneaky version of dogfight simulators : dodging pulse and doppler radars, awacs and fighter patrols, before striking your target and trying to get back to your base through a fully alerted enemy territory was as intense as any foot-based infiltration. The tactics are quite similar.
Just as with the top-down "Commandos" etc, it's worth mentionning that this sort of gameplay and tactical reflexion can be found in other forms than the usual fps or tps stealth games. And can be as stressfull and rewarding, providing a refresing change for the same category of thrill.
I was actually thinking of Jagged Alliance when I started this thread. I was hoping people would post different types of games.