And here are a couple of reworkings by TR Forum denizen jvjv:
Might be worth pointing out the obvious -- what's new is that people are encouraged by the interface to do this. The Nude Raider hack, and several less infamous versions, show this has been going on for a while.
I'm still impressed with the TR:C level editor (ported to the Mac by an arguably overly altruistic Glenda Adams, no less) -- TR has been allowing more and more avenues for player coauthorship, and that's often a very good thing.
Now off to dl that demo...