Here's 9 games that aren't my favorite games but games that I have strong memories of and are significant one way or another:
Sonic 3&K: This is a stand-in for other Genesis games of my childhood like Sonic 2, Rocket Knight Adventure, Contra: Hard Corps, and Ecco the Dolphin. The prototypical nostalgia game of my childhood.
Doom 1: Everything that has been said about Doom has already been said. But personally, this is a stand-in for all those DOS shareware games way back in the day. Doom was really really really good. Doom was also everywhere. I somehow got Doom 3 times, once as a compliation of shareware games, once as part of its own CD called Doom Fever, and once as three floppies that came with a guide.
Diablo II: This is a stand-in for Blizzard games when Blizzard didn't suck (Warcraft 2, Starcraft, Warcraft 3) as well as ARPGs. Diablo II is one of those games that I revisit over and over. It's also a game that I've modded. I remember spending hours on a DII modding forum trying to change how the game worked.
Shining Force II: This is a stand-in for emulation in general. SFII wasn't the first game I've emulated, but it was definitely the one that I remember the most by far and also one that I revisit every once in a while. It helps that the game is good.
Spider Soltaire: I don't think anyone was expecting this on the list, but hey, there were plenty of times in high school where I played Spider Soltaire, Minesweeper, and all those other games that came packaged with XP during high school, so it deserves to be on the list. This is also a stand-in for those Flash games that proliferated during the early 00s.
Arcanum: This is a stand-in for isometric CRPGs (Fallout 1, Fallout 2, Baldur's Gate, Shadowrun Returns: Dragonfall, Divinity: Original Sin) as well as Troika's CRPG (Vampire: The Masquerade). I mostly picked Arcanum because everyone else have already chosen Fallout 2. The entire genre defined my college years.
La-Mulana: This is a stand-in for Metroidvanias and indie games in general. I picked La-Mulana because when you tried to play it without a guide at all, it's really not a game but an experienceTM.
Stardew Valley: There's a period in my life where I did nothing but played Stardew Valley. There's a whole bunch of mods that I messed around with.
Minetest: This is an open-source clone of Minecraft that I've associated with Linux in general even though it wasn't the first Linux game that I've installed. This was the first game that I've tried to create my own mod, and there was a period of time where I would play this game while listening to Parenti's speeches, so there's that memory association as well.
There's also GTA:VC which is the defining high school game for me. And as for the dishonorable mention, there's L*ague for entirely negative reasons. Fuck L*ague.
There really is nothing else like Doom. It's not just that the game itself is still great after 30 years or that it was like a flash of lightning in the industry. It's a representation of community too. You don't just play Doom anymore, there's decades of wads out there made by people simply passionate about making good times. The scope of how many Doom maps are out there is awe inspiring and no one was paid a cent to do it.
And it keeps going. People keep finding ways to innovate in the scene. I hope it keeps going another 30 years.
I love Doom. I love the game itself, I love the music, I love the aesthetic, I love its place in gaming history, I love how it's simultaneously a product of its time and timeless, I love how its source code was released, I love how it's one of the earliest Linux ports, I love how it birthed modern speedrunning, I love how WADs had kept the game alive decades later.
The hype and accolades thrown at Doom are 100% warranted.