Peak-end rule
Also said as Duration neglect, End on a high
People judge a past experience largely by its most intense moment and how it ended, and they pay surprisingly little attention to how long it lasted. Kahneman and colleagues showed it with cold water in 1993, and with colonoscopy patients in 1996.
A player reviewing your game is reviewing the memory of it. It is a strong rule of thumb, not a law: a 2022 meta-analysis by Alaybek and colleagues found a large peak-end effect and almost no effect of duration, but also found that a plain average of the whole experience predicted memory about as well.
Say it
“The session currently ends on a defeat screen and a loading bar. Move the XP tally and level-up after the match and add the best moment replay, so the last thing they see is good.”
Where you’ve seen it
Peggle plays Ode to Joy in slow motion as your last peg goes. After a so-so level, that ending is what you remember.
Not to be confused with pacing
Pacing shapes how the experience feels while it is happening. The peak-end rule is about what is left when it is over.