TIM3 is the complete same thing than TIM2, excepted that this version is for Windows instead of Dos. Levels are the same, musics too, but there are just one difference : you can expand the play field in Freeform mode so that you can build larger machines. You can get it for free on
Lost Treasures FR in Image CD format. The website is in French, but the game is multilingual.
Return of the Incredible Machine : Contraptions is the same thing than the previous two games (TIM2 and TIM3), but with a few more things : new musics, a little bit of new puzzles, improved graphics and a new interface. The other levels are the same and the parts are still the same. My personal opinion : don't buy it. Instead, find for it and download it as buying it is a waste of money.
The Incredible Machine : Even More Contraptions is the best TIM ever. LOTS of new really hard puzzles with some more musics included. Interface is the same than ROTIM, but... anyway. This one is a must!