The nature of procedural level generation makes it hard for designers to implement a smooth difficulty curve. Instead, each level is treated as a static plateau of difficulty, with large jumps from level to level. With old-fashioned hand-placed levels, designers can create scenarios that have a much smoother flow of difficulty, even within the same level. But Dead Cells manages to get the best of both worlds: randomly generated levels with self-contained difficulty curves.
WARNING: Spoilers for late-game enemy types.