Single player games only and only once I complete the main story and any side quests that I wanted to do, only then I install stat or mechanics altering mods for a new variety of play. Graphical or visual mods I install immediately, I don’t consider those as cheating. Funny enough “cheating” in Skyrim has become one of my most played games in itself. I maybe played 5 hours at most of actuall Skyrim, yet have spent over 900 hours modding, breaking and then fixing the game. This involved anything from Thomas the Dank engine ramming a Sylvari in more way than one to modifying actions and scripts where everytime an NPC says the phrase “dragon” the game would summon a dragon and who will subsequently Fush-Roh-Dah their asses across the map to the top of a Whiterun building.