Right, since there's so much interest, let me say: it's gonna be a map! About mapping! A Black Mesa style facility, with loadsa sections where you can see, say, two identical elevators, one in-game and one Hammer-style, with all the p. ents. represented by func_illusionaries, massive multi-brush-scaled-down screenshots of Hammer for certain things... sound interesting?
Should be a lot more fun to do than a normal tutorial, too!
Vassy; was this the same idea you had?