Assassin's Creed series, Prince of Persia (2008, The Forgotten Sands)
The only tool you'll need is ArchiveX, it's a tool that lets you open the .forge files of the games and extract models and textures in various formats
If you have a 32 bit OS you'll find the tool here: 32 bit ArchiveX otherwise, if you have a 64 bit OS: 64 bit ArchiveX
A new tool from the same authors of ArchiveX is released, it's called Archive neXt and it adds support for Unity.
Here's the link: Archive neXt. There's also an importer for 3D Studio Max if you want to use the .arx format: arxImporter