Depends on the genre. I’m not the most cosmopolitan gamer out here, so my experience is reduced to a few areas.
Action Platformers/Vehicle Fighters: Mostly like you said. When I started playing these games I thought that they were monsters, whereas now I can do a lot of what I considered impossible without even breaking a sweat. It’s usually a matter of playing enough until my reflexes adjust to the specific gameplay and I catch the usual patterns in my enemy’s movements. The difficulty depends on how much I am forced to concentrate mentally and physically on what I’m doing.
RPG: Quoting TD, ‘RPGs aren’t difficult by definition’. There’s really not much you can do here, either you create a level cruncher, designate a specific (And usually constrictive) fighting method that the player must figure out, or simply program hit-or-miss battles that are up to your luck. The absolute best you can do is a game that is doable without excessive planning but still makes you think about your moves (Xenosaga 2 would be a fine example if it were less of an exploit whore). Basically, battle systems that allow you to influence things beyond your stats (Grandia/Xenosaga 2) are about as good as I’ve seen.
TRPGs/RTS: This is interesting. In these games you should never be allowed to have the means to obliterate your enemy completely, but instead be forced to employ your resources with inventive way beyond what you would use in an RPG. The RTS genre has great examples while the TRPG genre fails horribly at it, at least in my limited experience. In this case, the difficulty depends on how much I am forced to think ahead and exploit all the resources.
Black Isle/Bioware RPGs: No matter what the heck you do, these either need extreme patience to chip away at your enemy from afar, or an extremely good combination of preparation and ability to respond at the situations. It would be an awesome genre if it weren’t for the fact that, no matter what you do, you WILL see the endgame/reload screen every five motherfucking seconds since they usually require you to experience the five hundred ways your enemies have for killing you before even having a shot at winning.
Graphical Adventures: Puzzles. Some games require me to use a lot of logic while some others demand a more imaginative, childish mindset. Difficulty depends on how many hours do I have to spend staring at the static screen until I figure that I have to use the burning wood to ignite the rum and therefore create a bomb near the rubber tree that would allow me to beat the Scottish pirate.
The satisfaction I draw from each genre is relative. RPGs are for the bragging rights, which I don’t give a crap about. Black Isle/Bioware games are so frustrating that I’m too numb to even have a reaction at my victory. The RTS and Graphical Adventures are satisfying in an intellectual level, but nothing, NOTHING beats that tingling feeling in my legs that I get after beating the Action Platformers’ do-five-hundred-movements-with-absolute-perfection-or-you-die challenges. Again, beating the Megaman Legends 2 Class S Test was one of the most satisfying gaming experiences I’ve ever had and weren’t related to a magnificent plot.