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?
Some I’ve modded besides what you said (Bethesda RPGs would be like, 8 games or something for me) would be Cities Skylines, Deus Ex, Factorio, Stardew Valley, Mount & Blade, Terraria, S.T.A.L.K.E.R.: Shadow of Chernobyl, Stellaris, Oxygen Not Included, Project Zomboid, Darkest Dungeon, Kenshi, Battletech.
Factorio is one that adds absolutely tons of content through mods. Some change the game pretty significantly too
Mods are almost a must with Stardew Valley. There are so many QoL improvements to be had, world expansions and automations to remove some of the tedious busy work.