тут вроде было немного по теме, ретроспектива на примере двух игр от OHM Games:
https://www.youtube.com/watch?v=Xhd_Id_7obc&feature=youtu.be- Replayability through randomness
- Sense of progression: hand-made levels, boss every 5 levels, environment change
- Discovery: colors, weapons, enemies, updates
- Sense of accomplishment: feels challenging, but really is easy; 80% win rate