Are you sure you want to do this? Many old Macintosh games run fine under Sheepshaver, Basillisk and mini vMac. Macintosh repository has an online emulator for Macintosh games released up until Mac OS 9 . Archive.org also has an online emulator for Hypercard games and applications. Furthermore, many of the games you have played most likely have Windows releases which are much easier to run or emulate. There are even games by Pangea Software that have been remade for modern systems which you can download for free right now. You can save yourself the trouble of emulating by looking for a second hand Mac OS X computer that has PowerPC compatibility.
...Still here? Fine.
For this tutorial, you will be running QEMU and emulating Mac OS X 10.1 Puma. This is because QEMU is currently the only emulator which allows you to have sound. Furthermore, as far as Mac OS X versions go, Mac OS X 10.1 works best under QEMU.
Download the latest QEMU package from here. Make sure that you download the QEMU Screamer build which is located under the experimental builds header.
Download the empty Mac OS X .img file from here . Also download the .iso file for Mac OS X. Copy both files into your directory where QEMU is located.
Open qemu.bat in an editor such as Notepad ++. Copy and paste the following text into it:
Now, save your file, then double click and open qemu.bat. You will now be able to install Mac OS X 10.1. Proceed through the installation as normal.
Once you're done installing the operating system, close QEMU and open qemu.bat again in your editor of choice. Change boot d to boot c so that it doesn't loop through the installation process every time you start up the emulator. If you want to transfer files to your emulator, edit the name of the .iso from the name of the installation disk to whichever file you want. Keep in mind that your .iso file name shouldn't have any spaces so be sure to change it from "My cd.iso" to "Mycd.iso". Save the qemu.bat file once you're done and open it again.
This should be enough to run programs that are too new for Mac OS 9 but far too old for Mac OS X computers without PowerPC compatibility. However, I haven't been able to get Classic Mode (for the purpose of emulating games such as Alone in the Dark and Cro-Mag Rally) to work properly up until now. If you still experience problems emulating or want to do more with the VM such as use the internet, have a look at the emaculation forums.