Yeah, our machines are old and don't have the sheer power of a new quad core iMac. But they can still play some cool games. I'll just toss a few of my favorites for you to find copies of and enjoy.
Last Updated: 4/23/2016
Fallout is one of the best classic RPGs ever created. It's an engrossing, detailed story with a big world to explore and lots of options to make it different each time you play through. You should be able to find a copy on Amazon or eBay for cheap. Enjoy. You'll thank me for it later.
When you finish Fallout 1, go ahead and grab a copy of Fallout 2. Once again, the game gets even better, bigger, and more fun. What kind of character will you build? Both of the games were excellent ports by MacPlay.
The Marathon trilogy was created by Bungie long before Halo was a reality. Today, all three games are released free and have been enhanced updated graphics and more features. You can also find new story lines and levels to explore through user content. It's definitely worth a download.
Cave Story at first feels like a throwback/ripoff to those classic Nintendo games of old, but it turns out to be beautiful and compelling in its own right. This is a platformer with multiple endings, a fun story, and creative gameplay. And, yes, it's available for PowerPC.
Blades of Exile is an RPG engine from SpiderWeb software, makers of classic rpgs like Avernum. This is an older system, more of a flat tile based look than a 3d look. Still, it includes some starting scenarios, and you can make your own stories using the system. Lots of fun.
OotP Baseball is a free older version of the simulation heavy baseball management game. This thing is thickly detailed and can rob days of your life as you search for the best trades, fine tune your team, draft players, and manage a full professional baseball team. Heck of a lot of fun.
There are exactly two MMORPGs that work for PPC Macs (that I know of).
Oberin is an Ultima Online-like MMORPG that lets you adventure in a fantasy world, fighting various creatures and building up your character. The graphics are modest, so it should work on a variety of older Macs. The community also appears to be small and tight knit. Best of all, it's free to play.
Clan Lord is one of the longest running MMORPGs on the Mac. I remember playing this thing on my Performa 460 in college. Awesome stuff. It has a very strange kind of control system and very quirky world to explore. However, I was unable to get this to run on my G5, but others have had success. There is a fee to buy the full client to play.
ZDoom is a free, open source, enhanced port of the classic first person shooter, DOOM. Talk about a blast from the past. While you still need the commercial WADS to play the classic game, you can either download the old shareware files or grab new levels that take advantage of optimization and new features in the classic engine. Just a lot of fun.