Always wanted to take the Shadowgate/Deja Vu engine and retool it to make a WWII spy story in a German Uboat. 

What do you mean "retool the engine"? Would the engine actually work differently than Shadowgate?

It would be a lot of work to swap graphics, but I don't think Shadowgate reuses many backgrounds.

Redoing the music used the be really hard, but there might be some tools for that now.

You will have to become intimately familiar with hex editing, since that will be how you change all of the event triggers in the game, as well as change how backgrounds are constructed, etc.

ha! i think i'm the retool in this thread. i meant fix the event triggers, the game flow, as it were.

when i first played deja vu i was blown away- "it's the same bleeping game!" well, the same engine.

sheet, i'll check what board shadowgate uses, but the music might be as complicated as N106... or as simple as vibrato with the standard set (and some DMCs).

Don't forget that The Uninvited seems to use the same engine, as well. And the item count is considerably higher than Shadowgate. I'm guessing it might make a better baseline for your hack, since you will probably be limited by the amount of triggers that already exist.