First, some quick hit answers:
Stuck on a desert island: I'll put the PC aside, because it's obviously the right answer, and choose the SNES. Despite prefering the aesthetic of the NES more, the SNES has the greatest range of games I'd want to play. Beat 'em ups, RPGs, platformers, action-RPGs. I'd never get bored.
Challenging game that I liked: Sword Master for the NES. An obscure action-platformer with great graphics and very interesting combat mechanics. The game is punishingly difficult, but very quick and fun to play.
Challenging game that I disliked: Putting aside flat out bad games (like X-Men for NES), I would lump most shoot 'em ups in this camp. I don't have the twitchy skills to get through these games, so I mostly ignore them.
Too easy games: This is tough, as I'm no game whiz. However, WWF Wrestlemania for the NES is so short, with so little to actually do, that's it's easy to spam your way to victory over the CPU. Once you've won, the only thing left is to to do it all again or find a friend/relative to play with.
Manually ramping up the difficulty makes a huge difference in the fun factor. For example Gears of War....it was a decent game on Normal, but on Hard it was way better. The AI was much smarter so beating it was that much more satisfying.
I agree. I really found that I didn't have to really utilize the battle mechanics in the Mass Effect games very much until Insanity. At that point you have to understand the systems well, and use them to their full advantage. It does slow things down a bit, so I can understand why others choose to play on lower difficulty.
It's not just new games that hide gameplay behind difficulty gates. The much-maligned 16-bit beat 'em up genre did the same thing. Developers set the "Normal" difficulty in many of these games far too low, allowing players to button-mash their way through long enough to get bored and stop playing.
However, if you set the difficulty to "High" or higher, the real meat, it's bloody veins, are exposed. Enemy AI becomes more responsive while enemy placement/spawning becomes more devilish. In response, you have to up your game. You have to master the techniques the game affords you, like the "punch-punch-throw" combo in Final Fight or the air recovery in Streets of Rage 2. The game draws you in more because you're more engaged and, thus, having more fun.
Playing beat 'em ups at high difficulty makes them more resemble their fraternal twin genre the shoot 'em up, a genre known for punishing difficulty and exciting game play. Difficulty was the key to engaging play in shoot 'em ups, which was kept in the jump to home consoles. Beat 'em ups lost their difficulty when ported to home consoles. This simple difference in presentation is one of the key reasons why shoot 'em ups are still seen as relevant, engaging games and beat 'em ups are almost a lost genre.
"Groundhog Day games" I *dead* I hate *dead* I hate groundhog *dead* I hate groundhog day *dead* I hate groundhog day games *VICTORY!! A WINNER IS YOU!!
This is one aspect of retro games (especially NES games) that I do not miss at all. When I go back to play my old games, They'll feel totally familiar and I'll breeze through them... up until I reach the point I couldn't beat as a kid. Then it's like being dropped in a whole new game. I really was not great at video games as a kid, and the fact that lives and continues and my time were limited effected how far I could get in the games I owned.
This is why I have always been a very avid cheater. I had a Game Genie for my NES as a kid, and I have one for nearly all my systems now, not to mention using save states and cheats on my Retron 5. I understand the use of lives and continues as challenge in games. What I never understood was why they were limited. Sure, in some games, especially the Super Mario games, part of the game was earning enough 1-Ups to avoid the dreaded Game Over.
However, not all games had the option of earning new lives. Some had a very fixed amounts of lives. This always frustrated me. It seemed like nothing more than a waste of my time. Sure, playing through early levels over and over would make me better at them, but, no matter how many lives I could save up, I would watch them drain away in an instant upon reaching a new hurdle. Then I had to replay those early levels for a chance to practice what had killed me before.
I have no problem whatsoever breaking down these false barriers put down between me and enjoying my games. Rhythm is very important in playing games, and I am against anything that breaks that rhythm. I love Final Fight 2, to bring it back to beat 'em ups, but its continue system is broken. Arcade-style beat 'em ups rely on keeping you in the thick of the fight no matter how often you die, but when you continue in Final Fight 2, it sends you back to a previous spot in the level. I just turn on infinite lives and cruise right past that hurdle.