Download Batman - Arkham Asylum - Play As The J... __exclusive__ Access

was never officially released for the original PC version, but it can be added via community-made mods or configuration edits: Mod Installation:

When you download and access this content, you are treated to a completely different combat style. Download Batman - Arkham Asylum - Play as the J...

The Joker DLC is in the GOTY edition.

Not officially included in the Game of the Year (GOTY) edition, but can be restored using community mods. How to Download and Install on PC was never officially released for the original PC

Since the official methods are limited, the PC modding community created a solution. Here’s how to the necessary files to play as the Joker in the main campaign of Batman: Arkham Asylum on PC. Download Batman - Arkham Asylum - Play as the J...