My current project does just this.
There are a couple segments of the game that are quite linear (necessarily
so), and it's possible to get stuck without realizing it. I've included a
"Warning Mode," similar to score notification, that informs players of these
situations.
It's not designed to help with everything -- using a one-use object in the
wrong place doesn't activate it -- since that would give away too much of
what's important. It's up to the player to determine that, since nothing
happened as a result of his/her actions, it's probably time to undo or
restore. I only use Warning Mode to tell players they've screwed up when
there's a chance they can't determine that for themselves.
-- C.E. Forman ceforma@rs6000.cmp.ilstu.edu Read the I-F e-zine XYZZYnews, at ftp.gmd.de:/if-archive/magazines/xyzzynews! * Interactive Fiction * Beavis and Butt-Head * The X-Files * MST3K * C/C++ *