I remember when I first got Thief 3 about 15 years ago, Ion Storm saying that the game was not compatible with laptops. With all the patches, both official and unofficial, since then, I'm wondering if that's still true.

Ion Storm is long gone together with this statement about Thief 3 and Laptops.
Can for sure imagine 15 years ago laptops were a little weak to run the game, but today`s low/ middle range
laptop`s should be able to run the game playable if not very good playable :).
Mine is 5 years old and does not have any problems to run the game fluidly.

I remember installing it just to test on my work laptop back in late 2005/early 2006 and it worked.

I don't know whatever specs that laptop had, but it certainly wasn't gaming oriented in any way… and since by now it's a fairly old game, pretty much any laptop that's less than 10 or even 15 years old should be capable of running it.

this is your "may contain nuts" warning label. it just means you can't return the game in a "it doesn't work on my laptop" scenario. in case you live in the stone age and bought a dvd.

Okay. Thanks