Linux

Not really sure what would be your type of game but here's some that I've played that I found addicting, from various genres. All of these are on Steam and I've played on Linux.

Definitely look at Portal 2. Great game that's easy to get into.

If you played and liked Portal 2, also take a look at Portal, The Talos Principle, and Q.U.B.E. (I probably can't go wrong recommending puzzle games)

Maybe also Mirror's Edge (2008).

Baldur's Gate 3 is one I've put a lot of time into recently.

Chill exploration game that I couldn't put down and am still obsessed with: INFRA

If you think you could like base builder games: RimWorld, Factorio, Satisfactory

And then some absolute PC classics: Half-Life (1998, or you can also play the remake Black Mesa), System Shock (play the 2023 remake), Vampire: The Masquerade - Bloodlines.

Classicube for that simple block-building itch

Minecraft: Java Edition

Stardew Valley

Most addictive would be DoTA. You can probably find 10 million player with atleast 5k hours

Whatever floats your boat.
https://youtube.com/results?search_query=best+games+of+all+time

Oh, and go with Steam.

Strange that no one mentioned cdda, here's sseth review https://www.youtube.com/watch?v=Cyoj4-niEPc

Brood war ;)

I'm addicted to Minecraft and OSU. Every once in a while I'll play some risk of rain 2

TOME4 it is free (apart from the psychological toll if you play it on rogue-like mode)

Quake 3 Arena or if you don't want to pay/pirate just install openarena. OpenArena should come be in your distros packages

dead cells, holy shit this game i can't stop it lol, osu! too but only if you like rhythm games and factorio if you like building industries i guess

Bloons Tower Defense 6

Xonotic is a fun first person shooter, with gameplay similar to quake. It's awesome if you have a bunch of friends that just want to jump right into action amd random weapon upgrades

Honestly not sure if Guild Wars 2 works on Linux but if it does... It's free for the core game. Tons of play time there

Uh... Tux Racer if it's still on there.

World of Tanks Blitz.

You either would like it or not. Requires brain to play. Think Call of Duty only fast reflexes and low latency make no difference. Each game is around 10 minutes or less.

It is totally possible to play and enjoy for free, if willing to accumulate cash prior to getting tank at next level.

Free to play.

You will have to use proton. It works with it.