When I moved into my appartment I didn't have internet for 2 weeks. Played Minesweeper in that time. ~8 hours a day.
When I went to sleep or whenever I had an "idle mind" I saw Minesweeper playing itself in my head. Lasted for about a month till it finally stopped.
Honestly, Minesweeper completely destroys your brain.
Had the same with Tetris, though not nearly as bad. (Maybe 2 days long).
I was also thinking about how I would place Portals in the "real world", though those were rather conscious thoughts.