So.... How do I get it ?
The features available are quite extensive, and it is developed on Ubuntu (Kubuntu to be specific, largely for cross-platform portability with QT).
Sorry, but no .deb packages yet. Only source tarball.
You can find it here.
Yet another necro thread revival...
There is a package called Game Editor available for linux, that is similar to Game Maker. I haven't explored it too much yet, so I don't know if it's as powerful as GM is. I think it's definitely worth taking a look at, though...