A well designed gameplay, as any game designer will tell you, is not based on constantly going for thougher challenges, but to have ups and downs to strenghten the engagement and to have highs and lows. Not to mention how constantly just upping the difficulty level is more than a small hinderance for a well designed story... but I'm sure that's just because all people out there are pussies and sissies and not as though and smart as our friend here, who is a real gamer (btw - I'm so much in awe of people who are good at video games, these are the real heroes out there).
Couldn't have said it better
