„Flow“ is often regarded a valuable goal of game design, not least by prominent developers such as thatgamecompany. The theory says that you want to hit the sweet spot between overload and underload, not demanding too much from the player but also not demanding too little.
„Flow“ can not only fall apart when a game diverges from this sweet spot but also when a games‘ edges are too rough. A simple bug probably breaks „flow“ more easily than any other aspect of a game such as weird physics behavior. This is similar in other media such as books (when you encounter a typo), music (a misplay during a live performance), or film (a continuity error). Creators usually go to great lengths to keep these „fourth wall“-breaking aspects out of their work but – due to its interactive nature – games are probably the medium which is the hardest to keep free of such effects. Some games embrace this and consciously add glitches or similar errors in order to achieve a specific effect (e.g. Michael Brough games or „The Stanley Parable“).
An aspect that could support „flow“, on the other hand, is what I would call „continuous design“ where the game constantly evolves while playing. Where there are no individual levels, no binary input, no discreet decisions, only continuity. The game itself „flows“ and the player is invited to „flow“ with it. A game like an „Avalanches“ album where one track flows into the other, without hard boundaries, where all the samples and vocals and tracks blend in and out; like sun and clouds and rain and snow do on a wild day in April.