I guess this is a bundle, it's labeled as such, even though it is only three games: https://www.fanatical.com/en/bundle/doom-bundle
Tier 1 is Doom 2016 for $10. Then for $10 more you get the Doom Classic Complete that has Doom 1 and 2 along with a number of bonus levels for both as well as the re-release version of Doom 3. Not a bad deal.