After upgrading the game to v1.9 via automatic update, you can download and install the DX11 Ultra Upgrade, which adds features like tessellation and displacement mapping, realistic shadows and more. To amp things up even further, grab the Hi Res Texture Pack, which includes impressive graphical improvements whether you're using DX11 or DX9 (64-bit OS and at least 768 MB of video card memory required). Check out the trailer after the jump to see what's in store.
Download the Crysis 2 DirectX 11 Ultra Upgrade (545 MB)
Download the Crysis 2 Hi Res Texture Pack (1.65 GB)