I was reading this article on Tom's Hardware here.

http://www.tomshardware.com/reviews/crysis-3-performance-benchmark-gaming,3451.html

It mentions early on in the article that the game will give even the highest end of machines a run for their money.
So what I don't entirely understand is this. How can you make a game whose settings can exceed what the most advanced hardware can even render?

How can you make a game whose settings can exceed what the most advanced hardware can even render?

How can't you?

I am sure that if the game was optimized, we can gain more FPS.

So what I don't entirely understand is this. How can you make a game whose settings can exceed what the most advanced hardware can even render?
You mis-understood it, there is no game that our technology can't render. The problem is rendering it at a playable framerate.

The best example is the original Crysis. At the time the best single-GPU card was an 8800 GTX, but if you maxed-out all settings to Very High and resolution to 1920x1080 and AA to 8x, you would get around 10-15 fps - unplayable.
The GPU rendered everything just fine, it's just that the rendering was taking way too LONG. That's why they game was stamped with "graphics ahead of it's time", because to fully max out Crysis at smooth framerates you needed a GPU setup that didn't exist at the time. CryEngine 2.0 could keep scaling as hardware became more powerful, you could keep ramping-up the polygons/shaders to absurdly high amounts.

CryEngine 3 is similar to that, though not as ridiculous because the fastest cards today (GTX690 and Ares) can run it fully-maxed at 1080p/8xAA at playable framerates. Hell, you can grab Titan SLI or 690 SLI and pretty much destroy the game at any resolution...if you've got $2000 to blow

It is optimised it's just that Crysis 3 uses a lot of heavy, advanced effects and more accurately. Pretty sure there is no game to match the Crysis 3 when rendering them all at one time.

- Tessellation with displacement mapping.
- Parallax Occlusion Mapping with silhouettes.
- Screenspace Directional Occlusion (SSDO).
- Real Time Global Illumination.
- Bokeh Depth of field.
- Fog and water shadows.
- DX11 MSAA with coverage sample(very heavy with deferred rendering).

Those are just a few but they're very GPU heavy.