The Altered Learning project is one project (in the UK of course) using the Neverwinter Nights game engine. I found this through the Learning in Immersive Worlds report, which was so recently posted on this very site!
I think the key is the spin-off learning activities that the students are required to do - they are still required to record their responses. Can a library mod transfer accomplish the same thing without curriculum support? Would students be AS interested if the long-term value was not easily recognizable?
"Altered Learning does just what is says on the tin. It provides effective alternative learning and teaching tools with the characteristics of a game, yet with the content of the traditional curriculum.
It’s a difficult balance to achieve but by modifying a commercial adventure game it has been done with great success.
It all began as an attempt to engage some rather reluctant learners. When teaching key skills in communication and application of number, learners much prefer to be sitting in front of a computer than a workbook, so a game was ingeniously devised that required the learners to learn by having to get through traps and pitfalls. The engine in the award winning Neverwinter Nights computer game had intricate coding incorporated in its programming so that the game produced a lot of the evidence for recognised KEY SKILL qualifications."