Asklemmy

Factorio 2016

I had to check my library to make sure which one is the oldest, but it's fallout 1 :3

Another World, my fav!! 🥰🥰🥰 the friendship, the bond... plus imma physicist 🤭🤭🤭

Sid Meier's Colonization. It seems every few years I always go back to it.

Also, honorable mention for Sonic 3 & Knuckles.

Both from 1994. Yeah, I'm old.

1991's arcade hit and genre creating game, Street Fighter 2

Does OpenTTD count?

Jak X.

On a regular basis, probably classic DooM / DooM 2.

Heroes of Might and Magic III

Worms Armageddon

Command & Conquer: Red Alert 2

Garrys Mod. You'd actually be impressed how many people still play that game for it approaching its 20 year anniversary.

Started playing Spelunky HD again the other day, the sequel is better but the original is still fun to revisit.

Morrowind and Fallout: New Vegas sometimes. I've tried playing the original two Fallout games but I keep bouncing off the first hour or two.

Some Guilty Gear XX AC+R with a friend -- we would love to play some old Tekken games too but we're both on PC so Tekken 7 is the oldest available.

Every once in a while I'll play some Sacrifice, such an amazing game that's dying for a remaster.

I regularly go back to Warcraft 3 in between playing newer games if somethung piques my interest or gets a cool update.

Spent so much time playing both campaign and custom games over the years since release, and finally got into melee/1v1 about a year+ ago

The fact that the game actually gets support with balance changes and updates again has been lots if fun

Mario Kart: Double Dash!!

Carmaggedon(1997), via a reverse engineered dethrace

Gothic

Crash Bandicoot 2

The oldest single player game I keep going back to is Super Mario World on the SNES, Copyright 1990.

I will occasionally play games older than that, but the SNES is where my actual nostalgia begins.

Freeciv

Gothic 1 and 2 (from 2001 and 2002 respectively) are still some of the best games I ever played. There is also a very active modding community, and some mods are even much better than the original game.

Solitaire and Minesweeper. Literally the best games for when I just want to play something that doesn't require a lot of attention (no story lines, long load times, or remembering what I was doing the last time I played). Just enough to focus my attention while waiting around, but able to close out when whatever I was waiting on is ready. Just really calming for the most part.

Robotron 2084 - there is a place by me that still has the arcade cabinet.

Currently playing Hot Wheels TURBO Racing (1999) on the N64 (Analogue 3d). It's a good little arcade racer and has been fun to hop back into it.

I regularly play Might and Magic 4 and 5: World of Xeen. It's from 1992.

I still play NES games often. These were the games of my childhood. Balloon Fight and the original arcade Mario Bros. are always fun for shorter sessions. And I still enjoy playing through Super Mario Bros. on occasion. I very rarely have ventured into games older than the NES.

Mario 64 on original hardware. Never did finish it as a kid so no time better than the present

Joust.

I found an abandonware do of Risk 2 from 2000. Run great and is just as much fun as when I was a kid. A friend and I are going to try the network interface to play against each other.

Every few years I replay both Golden Sun and Golden Sun: The Lost Age.

Last three were Star Ocean (the first one), Radiata Stories, and Skies of Arcadia.

Currently playing Alundra because a friend grew up with it and wanted me to play it. Honestly it's not great but RetroAchevements made the bosses extraordinarily painful to master, which is uh ... fun. Yes. Fun, let's go with that.

Oh and ps these commenters all have fantastic tastes.

I generally play at least one of the Ultima games every year, mostly the late 80s and early 90s ones.

For a time it was Solitaire, but these days it's 2048.

OpenTTD