1. Please make sure you have the latest Parallels build;
2. Please install Parallels Tools via the "Actions" menu;
3. Please check the "enable direct x" box in the video settings,
It has basic Direct3D support basically from utilising WINE. So things that work with WNE will work and that's about it (with some variation sue to modification). Many games will have problems unless specific support has been implemented, or the game will fallback to older versions of DirectX with lower graphical features.