Early ones has Mac OS9 and later ones came with OSx.
The iMac G4 is able to run any version of Mac OS X up to and including, version 10.5 (Leopard).
It runs on the OSx operating system. It would not be an iMac if it ran on Windows or any other system.
NO!
The G5 came with the OS 9 operating system and had a Power PC processor. It was the last edition of Mac OS. The iMac switched to the OSx operating system with the next iMac. There was an education only model G5 that did ship with OSx Panther.
Sims 3 will not work with a G4 iMac. The game requires a recent Mac with an Intel processor.
Turn it on by pushing the power button on the back left bottom of the iMac.
It depends on your operating system.
Intel microprocessor-based computer running the Apple Macintosh operating system; Intel-Macintosh computer; IMac computer; iMac computer
If a G4 iMac is working but starting up without the chime it may have been shutdown with the sound muted or there may be headphones plugged in. If it is not starting up at all then it will need repairing.
Morrowind is only available for computers running Microsoft's Windows operating system and their Xbox 360. It is not compatible with the G4 iMac running Mac OS X.
I think the oldest imac I recommend is the iMac g4 (only if it's running tiger) you could purchase one on eBay for about £65
iMac, Mac Mini, Macbooks, and Hackintoshes.