Minimum Requirements:
Windows 98/2000/XP, Pentium III or Athlon 1000 MHz
ATI Radeon 8500 or GeForce 3 or higher
128 MB of RAM
256 MB for XP (256 MB, 384 MB for XP recommended)
800 MB free Reader CD-ROM or CD / DVD-ROM 8X
Microsoft DirectX 9
compatible sound card DirectX

Recommended Requirements:
Windows XP, Pentium IV 2.8 GHz or Athlon 2.8 GHz
RAM 256 MB
Graphics Card nVidia GeForce FX 5900 / ATI Radeon 9800, 512 MB ​​RAM,
Sound Card compatible with 3D sound.

Download Link:
Download Roller Coaster Tycoon 3