Great read as always. I really do appreciate that you spend some time to explain the setup and conditions of the testing. It makes the test read as an actual study - and I think it is great.

I have always had this debate on tutorials X game flow. I feel that stopping the gameplay to teach tends to break the flow, even for the sake of explaining. At the same time, there are some gameplay that are so hard to streamline without stopping the play for a second. Do you have any thoughts on it?

I understand you even suggested having more of these tutorials for really beginners, but having players to question their skills without knowing the game is also not a problematic approach? I am a total beginner in Doom (I'm not huge on FPS), but I am not a total beginner in games, then I would get most elements without a tutorial based on previous experiences.