Okay. Start with first-person shooters. That’s an easy one.
Operation Wolf (arcade) - This is widely credited as the first true arcade FPS. Of course, given that Taito had absolutely nothing to go on, it inevitably would have…flaws. See, the problem was that there was no sight on the screen, so it was next to impossible to get any level of accuracy, and it was easy to take a ton of damage if you didn’t take out enemies VERY quickly. Oh yeah, the only way to clear a stage was to get the required number of enemies…reset if you continue, of course. The end result was a game where roughly 99.999% of the players got absolutely slaughtered in the second stage. I witnessed ONE player make it all the way to the sixth and final…and die, over and over and over, never coming close to beating it.
Lethal Enforcers 2 (arcade; PSX probably even worse) - The successful template was already in place, so Konami only decided to make a few tweaks for the sequel…normal enemies that could take 2 hits or 6 hits, vastly increased speed, and plenty of truly dirty tricks involving the innocents. And some seriously painful bosses. Worst of all, the enemies continually get faster on the draw the longer you go without taking a hit, which means there’s NO way to evnetually avoid taking a hit. I don’t know anyone who was able to get to the end of this without shovelling in tokens.
CarnEvil (arcade) - “Evil” was the right word. A bazillion pop-up enemies coupled with some extremely tenacious bosses and subbosses made getting through economically a lost cause. Oh, and you have a lifebar for it, and you know what that means.
Terminator2 (arcade and Super NES) - About 20 enemies on the screen at any given time, a thousand ways to die (particularly the much-hated truck level), and some majorly diabolical bosses (particularly the overwhelmingly loathed helicopter).
Also like to give a nod to the entire Gradius series, although that’s more “colossal pain in the butt” territory.
Bayou Billy was definitely one of the harder NES games, but I’m not putting it with the real monsters since there definitely were ways to beat all the challenges. Even the goon duo at the very end (who have nothing on The Count). Here’s a hint: Complete all the training exercises. They really do benefit.
More later…still sifting out all the “moronic design” cases. (Currently on the fence about Air Fortress.)