Once upon a time, I wrote articles for InsideMacgames.com during the heyday (if there was ever such a thing) for Mac gaming in the very early 2000s. Despite the relatively small audience, the landscape was much healthier as companies were more willing to port games to the Mac, which is a topic in itself. I never considered myself much of a gamer, but I enjoy them now and again and remember many of the major releases for the Mac.

This is a list of what I'd consider largely the best releases for games compatible with Mac OS 9 - OS X, ideally for G4 and G5s, although I'm sure G3s can play a chunk of the titles. Mac users often learned to give some times a second glance that PC enthusiasts may skipped as they had a much larger library to pick from. Also, I'm sure there's some classics or loved titles I skipped or forgot. This is by no means a complete list, rather games worth taking the time and installing.

If you're looking for a list of recommended games, on a nostalgia kick or new to retro Mac gaming then scroll on down. There's roughly 100 games in this list.

4x4 Evolution, 4x4 Evolution 2 - A slightly lesser known off-road racing title ported to the Mac
4x4 Evolution - OS 8 - OS 9
4x4 evo 2 - OS 9 - OS X

Age of Empires II: Gold Edition, Age of Empires III - The classic isometric nation building RTS by Microsoft, but it made it to the Mac.
AoE II - OS 8 - OS X
AoE III - OS X

American McGee's Alice - The horror sequel to Alice in Wonderland making clever use of the Quake 3 engine.
OS 9 - OS X

Baldur's Gate II: Shadows of Amn - Honestly, I haven't played this but it's so well loved that it clearly belongs. OS 8 - OS 9

Black & White (Platinum Pack) - A god simulator, I don't think I'd call this great or even good game but it's interesting for it's oddness. This same description could be applied to it's chief creator, Peter Molyneux
OS X

Call of Duty (Deluxe), Call of Duty 2 - Before modern warfare, it was humble World War 2 first-person shooter series.

Sid Meier's Civilization III - I installed this game once in college and lost 25 hours in a single week and deleted it, never to play it again. You have been warned.
OS 8 - OS X

Command and Conquer: Generals - It wouldn't be a computer gaming list without the C&C franchise on the list.
OS X

Descent, Descent II, Descent 3 - A vehicular combat game that is usually considered a 1st person shooter, with a fully 3D environment before Quake.
System 7 - OS 9 (Descent III, OS 8 - OS 9)

Diablo, Diablo II - The original looter, an RPG where you click on the thing you want to die.
System 7 - OS X

Doom, Doom II, Final Doom - "...But can it run Doom?" Yes, it can.
System 7 - OS 9

Doom 3 - It's very dark.
OS X

Dungeon Siege - A diablo-like dungeon crawler that seems somehat forgotten and had a few popular mods.
OS X

Duke Nukem 3D, Duke Nukem 3D (OS X) - It was a different time. We used to think this game was really cool.
System 7 - OS X

Deus EX - Videogames started to grow up, and Deus Ex helped lead the charge where actions mattered in quasi-cyberpunk RPG/FPS fusion.
OS 8 - OS 9

Escape from Monkey Island - The humorous LucasArts adventure series returns to the Mac again.
OS 8 - OS 9

Escape Velocity, Escape Velocity Override, Escape Velocity: Nova - the top down space exploration trilogy from Ambrosia Software.
System 7 - OS X

Fallout, Fallout 2 - An isometric odd-ball post-apocalyptic RPG, and we're all the better for this game having been made.
OS X

Future Cop: LAPD - a solid and often overlooked title that may not have aged beautifully but still worth a look
System 7 - OS 9

Glider Pro - The final evolution of a classic Mac series, where the user controls a paper airplane through houses loaded with obstacles and the ability to create your own maps.
System 7 - OS X

Halo: Combat Evolved - It's impossible for a Mac gamer who was around not feeling some sort of way about this title, or not to mention "It was originally a Mac game."
OS X

Homeworld 2 - a classic space ship RTS
OS X

Indiana Jones and the Emperor's Tomb - It's sad that Indiana Jones as an IP hasn't had the same level of quality as Tomb Raider. The game is alright, PC gamer seems to think it aged alright.
OS X

Kelly Slater's Pro Surfer - from the same team of Tony Hawk's Pro Skater comes the underrated surfing game,
OS X

Madden 2000 - The Mac rarely got love from EA Sports, and Madden 2000 is an outlier where EA tepidly dipped its toes in the Mac gaming market. It was an admirable port by Aspyr.
System 7 - OS 9

Maelstrom GPL (OS X) - an opensource version of popular game, Maelstrom with better OS 9 and OS X compatibility
OS 9 - OS X

Marathon Trilogy Box Set - "They're everywhere!" The most iconic Mac gaming series of all time. Also, check the AlephOne Project for OS X 10.2+.
System 7 - OS 9

Max Payne - A trope fueled romp of non-stop bullet time gun fights in a much loved 3rd person shooter,
OS 9 - OS X

MechWarrior 2: 31st Century Combat, Mechwarrior 2 (RAVE aka ATI) - customize giant tank-like robots, and battle other Mechs in a simulation/FPS style.
System 7 - OS 9

Medal of Honor: Allied Assault, Medal of Honor: Allied Assault - Spearhead, Medal of Honor: Allied Assault - Breakthrough - In the 2000s, World War II was very much in the mind of gamers and gamers universally agreed the Nazis were still bad guys.
OS 9 - OS X

Myth: The Total Codex (Myth: The Fallen Lords, Myth II: Soulblighter + Chimera), Myth III: The Wolf Age - Bungie's 3D real-time strategy, with its quirky brand of chaotic battles.
System 7 - OS 9 for Myth 1 & 2, OS X for Myth 3.

No One Lives Forever (The Operative), No One Lives Forever 2: A Spy in H.A.R.M.'s Way - fairly forgotten FPS that had good Mac ports.
OS X.

Oni - A somewhat unfinished game but still a fun 3rd person combat game from Bungie.
OS 8.5 - OS X

Quake, Quake II, Quake II (OS X unofficial), Quake III Team Arena, Quake III Team Arena (OS X) - Each game is wildly different to the point where I could have written a word or two about each game, but let's be realistic, you already know the Quake series.
Quake - System 7 - OS 9
Quake II System 7 - OS X
Quake III - OS 9 - OS X

Red Faction - A sci-fi FPS with destructible environments and vehicles.
OS X

Return to Castle Wolfenstein - A solid remake even if occasionally thematically silly and a lot of fun. Make sure to check out the massive amount of add-ons.
OS 9 - OS X

Rollercoaster Tycoon 3 - Probably the strongest of the sim games under the Tycoon umbrella.
OS X

Shadow Warrior - From the makers of Duke Nukem.... Again, it was a different time, but even at the time, it received negative reactions for its (charitably speaking) humor, which relied on stereotypes. This is more of a "We've come far from here" when it comes to the portrayal of various groups in games.
System 7 - OS 9

Sim Ant - Greatest game of all time. It's one of the earliest RTSes and a game that really needs a sequel. You manage an ant colony, which, unlike most Maxis games, has a clear endgame: To clear the map of both the red ants and humans. Silly mode is a must.
System 7 - OS 9

Sim City 2000 - Absolutely one of the best sequels ever made, with its surprisingly melancholy jazzy soundtrack and irreverent humor
System 7 - OS 9.

Sim City 3000 - Another winner for Maxis in its city simulator series,
System 7 - OS 9

SimCity 4 + Rush Hour Expansion - The famed city simulator goes 3D,
OS X

StarCraft - Blizzard's groundbreaking Sci-Fi RTS.
System 7 - OS X

Star Wars: Dark Forces - It's very much a Doom rip-off mechanically speaking, but it's still a classic.
System 7 - OS 9.

Star Wars Episode I: Racer - Not every game is classic on this list, but being a Mac gamer often meant sometimes stooping to mediocrity,
OS 8 - OS 9

Star Wars: TIE Fighter - A flight sim but as the evil empire,
System 7 - OS 9

The Sims + The Sims: Livin’ Large - Maxis's quirky materialistic life simulator but on your Mac.
OS 8 - OS X)

The Sims 2 - The life simulation continues, and with so many expansions to download.
OS X

Tiger Woods PGA Tour 2003, Tiger Woods 2005 - Surprisingly, Tiger Woods PGA tour made it to the Mac a few times over the years, last seen in 2008. Tiger Woods 2008 OS 9 - OS X, Tiger Woods 2005, OS X

Tom Clancy's Rainbow Six: Rogue Spear, Tom Clancy's Rainbow Six 3: Raven Shield - a popular tactical shooter series aiming for realism compared to other first-person shooters of the time. Rogue Spear OS 8 - OS 9, Raven Shield, OS X

Splinter Cell - The 3rd person stealth 3rd person action/shooter made it's way to the Mac.
OS X

Tomb Raider (Gold), Tomb Raider II, Tomb Raider III, Tomb Raider Chronicles, Tomb Raider: The Angel of Darkness - Laura Croft made many appearances on the Mac made by the legendary Aspyr who's still working on Tomb Raider to this day.
Tomb Raider 1 -3 System 7 - OS 9
Chronicles/Darkness OS X

Tony Hawk's Pro Skater 2, Tony Hawk's Pro Skater 3, Tony Hawk's Pro Skater 4 - The legendary series made it to the Mac, THPS2 (OS 9 - OS X), THPS3 (OS X), THPS4 (OS X)

Tropico, Tropico 2: Pirate Cove - The fantastic dictatorial Sim-City-Esq Simulator. Tropico OS 8 - OS X, Tropico 2 - OS X

Unreal - This qualified for jaw dropping graphics in 1998. I played it in 800 x 600 with a Voodoo II, probably pushing 30 FPS in 16-bit color. It was great.
System 7 - OS X

Unreal Tournament, Unreal Tournament 2003, Unreal Tournament 2004 - Unreal got past its pretense for a story, much like Quake for a fun multiplayer shooter series.
Unreal Tournament - System 7 - OS X
Unreal 2003, Unreal 2004 - OS X

Virtual Pool - A simple pool game by today's standards, but 1996 was impressive, and while only System 7 - OS 8, can be run in OS X with the last update.

Warcraft II: Tides of Darkness - Blizzard's wildly successful sequel to a game almost no one ever played, classic 2D RTS.
System 7 - OS 8

Warcraft III: The Frozen Throne - The massively overhauled sequel to Blizzard's breakout RTS hit, Warcraft II.
OS 9 - OS X

WingNuts 2: Raina's Revenge - A small overhead shooter World War 2ish shooter that was an indie Mac game.
OS X

Wipeout 2097, Wipeout Rewrite (unofficial OS X) - A futuristic racer more known as a Playstation series,
OS 9 - OS X

Wolfenstein 3D - The game you know and love slightly upgraded, with two new weapons, 128 x 128 textures, a blaring dramatic soundtrack, and altered storyline.
System 7 - OS 9

X-Plane 7, X-Plane 8 - takes a special type of person to want to play non-combat flight sims but if that's your bag, then X-Plane is pretty much the beginning and end for the Mac.
OS 9 - OS X

World of Goo - A classic indie puzzler and it works on PowerPC.
OS X

Zoop - fun little puzzler that was a bit of a flop despite being a good way to kill 5 minutes.
System 7 - OS 9

You'll notice that Nanosaur, Bugdom, and Cro-Mag Rally are not on this list. That is because they're not good. Seriously.