I have plans for a World War One stealth game...

[Petike]

Hey BTW and OffT: have you played a lot of Thief fanmissions? Any in particular you would recommend? I´ve only played "Thief 2X: Shadows of the Metal Age"... it was quite awesome! I recommend it.

I hope you mean it's the only fan mod of Thief, that you ever played. :

There are tons of FMs for Thief II, and somewhat less for Thief I and III.
Thief III missions are overall high quality ones. FMs for the first two games are a more mixed bag : Some are total amateurish crap, some are standard, but fun... and some are bloody brilliant and absurdly detailed, even surpassing many of the original missions (as long as level design and features go).

I think the best you can do, is visit some of the sites dedicated to Thief FMs and choose something that could appeal to you. Practically all of these sites offer up to date fan mission reviews as well, so your chance of downloading a quality mission is pretty much guaranteed.

Here's a useful list of FM sites :

http://www.thief-thecircle.com/
http://www.ttlg.com/forums/forumdisplay.php?f=100
http://www.thief-thecircle.com/missions/2007fms.asp
http://www.ttlg.com/forums/showthread.php?t=120908
http://www.ttlg.com/forums/showthread.php?t=121972
http://www.ttlg.com/forums/showthread.php?t=123356
http://www.keepofmetalandgold.com/
http://www.thiefmissions.com/
http://southquarter.com/

And you'll need to download and install the GarrettLoader program to play FMs :
http://www.potterdevelopments.org.uk/fm/main.pl

Everything's for free, Garrettloader doesn't require much space, just pay attention to the manuals and readmes and if you're in doubt, visit the appropriate Thief forum on TTLG.com.

And enjoy. :