I'm not sure to understand the issue here but D3DX9_43.dll is not the file you're gonna want to open, the one you should look for is The Aftermath.exe.
I think I fixed that problem, but now when I try to open the game there is an error "error 0xc00007b". I really wanna play it already haha I'm literally trying to do everything to make it work. It sounds like an awesome game