: Programs that look like the game launcher but install background keyloggers.

Modified to handle memory allocation better on modern Windows.

Early patches and cracks designed to remove the defunct GFWL dependency required the original DX9 executable to function. The Modern Reality: Steamworks Update

The DirectX 9 executable usually fails for one of three reasons:

Sometimes, aggressive antivirus software flags game executables as false positives and moves them to quarantine. Open your antivirus history or protection logs. Check if re5dx9.exe was recently blocked.

If you have a high-refresh-rate monitor (120Hz, 144Hz, etc.), the game's physics can break horribly. Enemies might become invincible, and co-op QTEs can become impossible.