I've seen the main list and The Treasures Of Montezuma 3 is not there, and is a game that can be played without the Steam application running. Actually, it is recommended to do it that way because is has a nasty memory leak problem (bug?) that was never fixed. Over time the game consumes more and more memory, and when is near 2 GB starts with sounds problems and soon when it reaches 2 GB it crashes. When Steam is running in the background this happens around at 30 minutes of playing, but without it, it takes much longer than that. So once the game is using more than 1 GB of RAM it's better to quit and close it to save properly, and re-launch it, to keep playing.
I've tested this myself, you only need to create a shortcut somewhere to the main EXE or execute it directly with Steam closed, and that's it. No Steam involved, because it's never launched along with it.