When I picture "the learning curve" graph, the x-axis is "time" and the y-axis is "proficiency". A skill with a steep learning curve is one where the graph skims the x-axis for a while, but at some point (when enlightenment is reached) the graph shoots up, with proficiency increasing exponentially. Chess (and other strategy games) are like this - much easier for an expert to improve her game than a novice. Games like Othello and Go, on the other hand have a graph where proficiency rises quickly at first, but soon plateaus (or continues rising, but slowly) - "a minute to learn, a lifetime to master" kind of thing. Saying that something difficult has a steep learning curve is misusing the phrase, not misdrawing the graph, IMHO.