While Spore (the full game, not Creature Creator) states that it require OS X 10.5.3, it's possible to get it running on OS X 10.5.2. I thought that I'd try to get it to run under 10.5.2 first in case it was possible, so I wouldn't need to upgrade. Unfortunately, 10.5.3 and later breaks compatibility with Starcraft, Diablo and some other older games on Nvidia 8x00 graphics.
Here's how I got it running in 10.5.2:
- Insert the CD, then using Terminal or something that can see invisible files, copy the whole contents of the CD to your hard disk, to somewhere like /Spore/.
- Navigate to /Spore » SPORE(TM) Install.app » (Control-clcik and Show Package Contents) » Contents » Resources.
- Open tgInstall.plist in your favorite pure text editor. Comment out the $INSTALLVOLUME line, as shown below:
<key>InstallVerify</key> <array> <!--<string>$INSTALLVOLUME/installer/INSTALLDATA.tgz=6352d7a8f78e9750444ba8aa26806a7201dd66fb</string>--> </array> - Find and replace $INSTALLVOLUME throughout the whole document with /Spore (or the full path to wherever you copied the contents of the disc).
- Change the MinimumSystemVersion so that the "string" line reads 10.5.2.
- Install the game!
<key>MinimumSystemVersion</key>
<string>10.5.2</string>
It's working fine for me on 10.5.2 with an 8800GT video card, but your mileage may vary, of course.

