Generally, the best way to get old games running on OS X is through a DOSBox wrapper like
Boxer or some kind of Windows emulator (VirtualBox, Fusion, Parallels Desktop, etc.). For Mac-specific stuff, there are also emulators, such as Mini vMac for Classic-era hardware and SheepShaver for OS 9.
The Mac's never been great at backwards compatibility, versus Windows and its attempts to get everything running from the dark ages onwards. Both approaches have their benefits and pitfalls, but the Mac's certainly weaker at playing old games. (Mac fans of old console games should check out
http://openemu.org though—it's very promising.)