Oblivion, kinda Vanilla+. I have a depressing number of hours dumped into Morrowind and Skyrim, but Oblivion has kinda always just been "there" for me. That game that came between. I've beaten it in the past, enjoyed abusing things like paintbrush steps and all that, but never got really invested. Couldn't tell you why.
So, I've decided to change that. Taking it slow, exploring, and just having a generally good time.