I guess you missed out on the original Deus Ex. It's still one of the deepest story-driven games ever made, let alone first person shooters. Every situation in that game had multiple, radically different approaches. The story had some significant branches based on your decisions, too.
The AI was a joke, though, but that now seems to add to the charm. It goes really well with the campy voice acting and over-the-top characters.
It's a game I'll keep recommending over and over again. The sheer amount of player choice, customization, and environmental openness and interactivity is tough to beat, even today.
Go back and read the GP. That comment was about FPSes not having "deep single player gameplay". Deus Ex most definitely had deep single player gameplay. Its AI was easy to game in hilarious ways (i.e. a joke) but that didn't take away from the gameplay depth. On Realistic difficulty level JC often died in one headshot so you still had to be careful not to draw too much attention.
The AI was a joke, though, but that now seems to add to the charm. It goes really well with the campy voice acting and over-the-top characters.
It's a game I'll keep recommending over and over again. The sheer amount of player choice, customization, and environmental openness and interactivity is tough to beat, even today.