YSK if you've seen something traumatic, playing Tetris for a couple of hours afterwards can drastically reduce the chance of it becoming a deeprooted memory and causing PTSD
A single dose psychological intervention, which includes using the computer game Tetris, can prevent the unpleasant, intrusive memories that develop in some people after suffering a traumatic event.
Is this too do with the focus you get from playing Tetris as well as the Tetris effect that can occur afterwards that'll keep your brain occupied so you don't think about the trauma as much?
When you see something traumatic, your brain will over the next few hours create images of the traumatic event. These images will come back to you as flashbacks over the years. Playing a game that requires high focus on visual details prevents the brain from creating those images, and as a result you'll get less (or not at all) flashbacks after the traumatic event.
I think you've summed it up brilliantly here. I'm sure anyone who's ever played a game like Tetris a little too long will remember closing their eyes to go to sleep and still seeing tetronimos! So I guess it pushes everything else out of the 'RAM' of our visual memory, including the traumatic stuff. No room for this horrid memory, the mind-cupboard is full of tetronimos now