exactly what it says on the tin GE64 implemented in the source engine. It's just gone beta so has some bugs but a brilliant idea and pretty well done to top it off
My bro dloaded it last year when it was still in the testing stages, so it was basically just wandering around the 'facility' level with nothing to shoot at. I think my bro was impressed with the look of the whole thing, it'll be nice to see how it's coming along.