D3x9-26.dll

This subtle typo is intentional. It allows the file to sit in a game folder without immediately alerting the user, as it looks like the required system file at a glance. However, Windows and the game executable know the difference; the game calls for the real Microsoft file, but this custom DLL is often injected or used to intercept those calls.

: Part of the DirectX 9.0c "D3DX" (DirectX Extension) library. d3x9-26.dll

A failed software installation or a system crash may have corrupted the file. This subtle typo is intentional