I have to say, I was sort of in disbelief during the game length discussion…maybe I’m the weird one here, but 12 hours sounds like a “normal video game” length, at least when it comes to a narrative-focused medium to high budget single player game. My immediate thought was more in the 2-5 hour range–a “short” game, for me, has less to do with the absolute length, and more with the idea of a lean, focused experience that explores one highly specific storyline and/or gameplay mechanism without any padding…something like INSIDE, for example. I guess the wording of the question specifically asks for the minimum length…I would probably place it closer to the 7-8 hour range before I start considering a game just a solid, brisk “normal length” game.
Side thought: Seeing as A Short Hike has become the canonical reflexive answer whenever anyone asks for a “short game” recommendation, I am quite surprised that more games don’t have “Short” in the title now!