The first step is always to look for prior art. Maybe someone had written a new ddraw.dll already, and I could just use it. As it happens, lots of people have, but nothing that's useful for me. Most of the ddraw.dll hacks are actually wrappers - that get between the game and the real ddraw.dll, change something subtle, but let the real ddraw.dll do the heavy lifting.
The point of these hacks is to fix small problems, like games that ignore surface pitch, require cleared surfaces or some such. In one case I found a forum thread claiming that deleting ddraw.dll from the game's directory fixes something, so in this case it's a hack gone wrong.
After further searching I found a project which actually released sources, with a liberal license even. It was a wrapper project (meaning, again, that they just call the real ddraw.dll), only supported DirectDraw7 and only very small parts of it, but it showed me how to get going.
I also dug up old DirectX SDK:s from my personal CD stack, as Microsoft has helpfully nuked all old DirectDraw documentation off the online MSDN. Thanks, dudes.
