Unreal is free on Steam and GoG now. The three biggest leaps in the history of the 3D graphics were Quake, Unreal 1 and Crysis (by order of appearance).
Pure 3d optimized and made for the first 3D graphics accelerators, really squeezed those graphics cards, and were ahead of their time and the hardware and directx (dx10 was based on what crytek asked)
To a lesser extent, Far cry / Half-Life 2 / Doom 3, are also quite there.
Had to mention this 'cos Cliffy B. worked on Unreal, I think.
Pure 3d optimized and made for the first 3D graphics accelerators, really squeezed those graphics cards, and were ahead of their time and the hardware and directx (dx10 was based on what crytek asked)
To a lesser extent, Far cry / Half-Life 2 / Doom 3, are also quite there.
Had to mention this 'cos Cliffy B. worked on Unreal, I think.