Offers the definitive remastered edition with 4K support, cross-platform multiplayer, and a built-in mod browser.
If you already own the game (the .wad files), you can use "Source Ports" to run it on modern hardware with better graphics and controls: DOOM + DOOM II on Steam doom-ii-download-pc-game-full-version-for-free
This is a 100% free, open-source alternative that uses the Doom engine but includes entirely original, free-to-use art and levels. Offers the definitive remastered edition with 4K support,