Steam

Factorio. I don't even need a second pick

The store tab and the library tab

factorio and rimworld. I can't believe that combo isn't here yet.

Ah, but would you keep Workshop access?

If so, Garry's Mod is almost cheating. There's a bit of everything in it.

So that and Warframe. I picked up WF ten years ago and it's still in my top ten recently played games. Though I have a love/hate relationship with the Metagame it turned into, it still remains.

RetroArch ;)

Fallout 4 and Civ VI

Easy

Slay The Spire for replay value and Rocket League for "pvp" itch.

Deep Rock Galactic and Pinball FX3. I'm tempted to put Baldurs Gate 3, but once you've done a number of runs, I feel like you'll be done with it.

Factorio.

So I'm going for longevity. These two definitely wouldn't be my first choices for top games.

Elder Scrolls Online and Minecraft. There is enough story, social, and creativity that I would hope it works out.

Once Baldurs Gate 3 gets solid modding, and assuming modding is allowed, that takes a spot.

I would say noita and beatsaber.

Dwarf Fortress and Dota 2

Satisfactory & Mass Effect

Slay the Spire and Noita

For longevity?

Satisfactory and Elden Ring.

Honestly, something like Call of Duty or fortnite might be nice too. I haven't played in years but the skill ceiling is very high so it could at least keep me occupied for a very long time.

Skyrim and Half-Life 2

Terraria and Starbound bc mods

I have a very specific taste

Binding of Isaac (flash) Binding of Isaac Rebirth

Literally thousands of hours of entertainment, pretty much

The Long Dark and Valheim

Dead Cells and Beat Saber. I don't know that I'll ever tire of dead cells, and beat saber my husband and I love to play together, trading off after three songs like we used with DDR when we were kids

Rimworld and M&B Bannerlords

I really wanted to fit Crusader Kings 3 in there, but I think ultimately these two cover all the bases, and have an amazing modding community to keep it fresh and interesting.

Slay the Spire would be the first slot where a lot of others could fill the second.

Factorio and project zomboid

Baldur's Gate 3, and um... Warthunder. Maybe Elite Dangerous instead of Warthunder. But why can't I play the $650 worth of other games that I bought and barely played?

Funny how there's a solid lack of quadruple "A" games here in the comments.

Does it have to be Steam? Or any two games?

Warframe is a good one. After 4000 hours I got burnt out of some of the things it does poorly and haven't played in a year, but overall it's fun with crazy new content on a regular basis for free.

Terraria has far more depth than I ever expected, and way more than that added since I last played. This game can sustain a player for ages.

I would say Satisfactory but I did actually get tired of it for a while. Itching to go back with the 1.0 release though. I love it but the two above have better longevity.

Dwarf Fortress and No Man's Sky. I wanted to say Satisfactory instead, but felt it might be too close to Dwarf Fortress in nature and that would make it hard to want to play either game if I was burned out from one of them.

Probably age of empires and MCC.

Torchlight2 and totalAnnihilation

TF2 and TF|2

Terraria and I can't decide between Skyrim, Fallout New Vegas or BG3.

No man’s sky and palworld

the talos principle 1 and automobilista 2

Stardew Valley (maybe not that if I can just use the Android version), Hyperbolica, Portal 2?

Skyrim and outcast (the old version by appeal studios)

Battletoads and Frog wars.

Skyrim and Witcher 3. Shoutouts to Baldurs Gate and Witcher 2, but the latter is far too short for me to want it on my "you can only play this" list, it's quirky but there's something special as hell about it for me. I've played it through about 15 times.

Beam.NG would be one just because it covers nearly every driving discipline and the other would probably be Cyberpunk. It’s not even that Cyberpunk is my favorite, but it has so much content in it at this point that it would keep me busy for years.