Puzzler is a puzzle game for Mac OS 7, 8 and 9, released as shareware in 1998. Last I checked, it ran fine under Mac OS X Classic, but you need to find some old hardware (or an emulator) for it.

Puzzler is no longer sold as shareware, you can register it with the name "Puzzler" and code "1054".

You can download Puzzler 1.0.3 as a StuffIt archive (120 kB).