Will Minecraft work?

I've given my old PowerBook G4 with 10.5.8 to my grandson. He wants to play Minecraft on it. I have looked and looked and written but I can't find out from the web site whether Minecraft will work with this OS on this machine. Will it? I am happy to pay for OS upgrades if that will help but they need to be by download since the optical drive doesn't work anymore.

Thanks

Carl