TES V Skyrim is an amazing game and one of my 'comfort games', I love the vanilla game (no mods), but mods can really make it shine even more and make it timeless. Modding Skyrim can be easy and at the same time complex, particularly mods that are "sensitive version". Bethesda's endless updates have made modding the Steam version a rather frustrating experience. When Skyrim was (finally!) released on GOG in 2023, it seemed like the perfect choice for modding free from Bethesda's updates... until the updates also arrived on GOG and the old versions (1.6.659) were also removed from here. It's like they pull the rug out from under you. I suppose the current version (at the time of writing, 1.6.1179) is "good enough" for modding, however there is no guarantee that Bethesda will make a new update, breaking everything, and removing the old version from GOG... AGAIN! If you don't intend to mod: 100% all the way, buy it on GOG. If you intend to mod: you might want to consider getting it on Steam - at least there you can easily downgrade your game.
