[QUOTE=Dj Yoshi]1) If you're looking for freedom and action, Deus Ex is THE game for you.
2) What you're wanting will almost never happen.[/QUOTE]
Yoshi pretty much hit it on the nail.
Deus Ex is probably the closest title with such freedom in an FPS. It's been my favorite game of all time.
The gaming industry doesn't stretch far beyond a general formula for the FPS:
1) You have between 10 - 20 different weapons but never more--nades, rifles, pistols, maybe fists or a knife/baton/sword, and rockets, of course.
2) In a single player game, you start with the weakest weapon and build your way up. The enemies also follow this natural increase in power.
3) Maps are linear. In some cases, the developers will be a little more thoughtful. For instance, no CS map has only one route from spawn to target.
4) The principle reason for playing an FPS is the adrenaline and fun of shooting things. To make it more sensible and civil, FPS's have stories or objectives in shooting up stuff. Some games give you options in the plot, adding numerous possibilities to the stories flow and conclusion; examples are DX, which worked great, and JA, which was mediocre. Still, the story is mostly a backdrop. When in HL2 did it actually matter that the resistance was growing against the combine? It just meant that you could shoot more stuff with more bots around you shooting stuff and more enemies shooting at you in a tighter space (run-on, lolol).
That's pretty much it. Feel free to add more. Overall, FPS's don't go beyond it, and yet it is my genre of choice