Classic DOOM has best Linux support of all games in my opinion. Because it was opensourced and plenty of great community-maintained source ports.

Doom has tons of amazing community-made content (WADs) made within last 30 years. Like what other games have mods that feature whole original soundtracks? It also has pretty competitive speedrunning and multiplayer scene. And some very, very difficult levels.

So to play the game you need port and also IWAD files containing levels, textures, etc. Official iwads are not free. So your options are

1. Buy D1+D2 on steam/gog, grab the iwads, ignore official source port and go play much better community ones
2. Pirate the iwads. Extremely easy, the files didn’t change since the 90s and have been shared all over the Internet.
3. First episode of D1 is free. Search for Doom Shareware. It’s packaged in some distros even.
4. Use the community-made iwad replacements from freedoom project. These are completely foss and also the website has some source port recommendations so probably start with them. I myself started playing DOOM with freedoom :)

a dollar or two per year

That exists? I only seen such price for first year only, then it’s normal 15$ or higher