Some games uses Dynamic Game Difficulty Adjustment to dynamically raise up or ler down the game play difficulty to always provide player with intense and thrilling game experiences. However this seemling clever move is not a good design as it invites a worse thing: it takes away the abilities of players to play the game by their will - to go in an easy mode to experience the game, to want the threathen of failure and death to enhance their excitement, or to use their acumulated rewards and advantages to defeat the mighty enemies easily. This will make players feel played by the game. Another bad thing is that players can not show to others how well they played, as there is no standard of game difficulty.
Example[]
Homeworld is a real time strategy game. Although it was a very successful game with multiple good new designs, in the game the number of ships that enemy AI begins with in each mission is set depending on how powerful the game deems the player's fleet to be. Successful players have larger fleets because they take fewer losses, and will face a very challenging enemy power. This design makes some players complain that they play smart and hard but get no rewards, and even worse some players delibrately play bad to make incoming missions easier.