The D3D render is the current one IO used for Contracts. It gives ambient fog, and limits frames. OpenGL was the original choice, as it was used for Hitman 2. Rain effects were supposed to be added to many parts of Contracts, and the rain window at the main menu was one of them. However, IO has started programming Contracts on the GL renderer. Only in mid production, they swapped over to D3D. That is why on GL, it moves, and the fog is removed, because GL was the original choice of render, but IO swapped over, and doing so, they forgot to animate most rain effects on this renderer. Or due to the limit of frames on D3D, some animations do not load. GL was used for the BETA builds of Contracts.