I know most of the Bethesda RPGs have massive mod support, and there’s games like Minecraft that have more mods than anyone can imagine. I would consider those games pretty playable in their vanilla states. Would you say there are any games that were “saved” by modding? Or that are still kept alive by thriving modding communities? What are some of your favorite mods?
Doom 1 and 2 would be a lot less interesting without mods, some of which change the game rather dramatically.
Without mods, these games would have just been historical footnotes, not something a significant number of people still play.