Haha, I actually experienced this after more intense periods of designing maps for Phantom Doctrine which were also grid-based. I remember looking at my environment and kinda subconsciously checking whether everything's properly placed in a 1.2 x 1.2 x 3 meter grid like in our game - noticing irregularities and too small gaps actually caused slight discomfort.

What'd be really weird would be to have a HyperRogue dream, since it takes place on a hyperbolic plane.

My most recent tetris effect was with Catherine. Great game!

I always thought that it would be more respectfully to call it "chess effect" because, obviously, Chess is older but the subject goes more about videogames and tetris is the main flag of this effect.

Gaze at the ceiling and think about chess knight positions and domains!(Chess) or just figure out tetris builds.. or (these days in my case) moving giant cubes to climb up in the smooth way (Catherine).
Standing at the supermarket queue and thinking this things and then "wake up" and say to yourself in your mind "what the hell I'm doing!?) ^^

The first Tetris effect I remember experiencing was with this little Flash game: Ball Revamped 2

And years later, this other one, by the same author: Exit Path (this one had a multiplayer that worked really great, too).

Interesting.

I have honestly felt this only very few times and marginally, like thinking about playing a certain game (usually one that requires careful planning) when I am half-asleep and cannot control my thoughts anymore, but it was a matter of minutes and it happened very rarely, like 5 times at maximum in my whole life.

I think the "Tetris effect" might be your brain trying to learn to play the game better while you sleep or are otherwise idle. The brain needs some time to process things, and the tetris effect is just the way the brain does this (in at least some people).

Apparently, I remember hearling on a twitch stream from an experienced TGM (Tetris: The Grand Master) player that eventually she stopped experiencing the effect; maybe it became second nature to her at some point? (For those not familiar, TGM is a series of 3 Tetris arcade games that are known for their extremely hardcore levels of difficulty, to the point where it takes years to master, and not even the best players in the world can beat TGM3's hardest mode consistently.)

I've experienced this many times:

Back in the day, after playing Quake excessively (started with shareware deathmatch) I would constantly calculate rocket launcher lead for all moving objects while walking down the street...

The latest would by Dying Light which sometimes send me into parkour mode IRL, constantly checking for holds and stuff to jump on, climb... (note that I've never done parkour/free running in my real life). That was actually fun, I had suddenly the feeling I was discovering my everyday surroundings from a new angle.

PS: I think this effect is connected to the principle "When you only have a hammer, every problem starts to look like a nail". When you play a game for a long time, it becomes your brain's hammer, and you start seeing its "nails" everywhere.

In shooter games with WASD control and mouselook, if you're experienced you can move sideways and still keep your sights pointed at a single point, thus moving sideaways and still keeping aim. I don't know the proper word for it, but it resulted in a strange kind of sidestepping I did when manoeuvring around objects and people on the pavement when walking through the city, in the time when I used to play Battlefield 1942 a lot.

It's called strafing, and if you go around an enemy firing at them all the time, it's circle-strafing.

Anyway, cool, thanks for sharing :-)

I don’t think it ever happened to me. When I was younger I did play several hours without a break and sure, after finishing I thought about the game but it was definitely not a Tetris syndrome. Nowadays I mostly play for half an hour, maybe a bit longer and while I like playing I’m not that engaged. Frankly, if it ever happened to me I would probably take a long break from gaming ;)

I sometimes try to ctrl-z my writing and drawing mistakes in real life.