The Difference Engine was one of the first alt-history/steampunk books that I ever read; and it pretty much gave me a permanent taste for both. I suspect that the maps help: I love alternate history maps.
And so adieu, GURPS Basic Set: Characters, Fourth Edition. I have not forgotten why I was thinking about you, never fear.
I really, really loved The Difference Engine. If anyone wants to recommend another in the same genre, I would appreciate it.