In my case, this dubious award goes to
Cannon Fodder.
I didn't play it back in my Amiga days, unfortunately (though I remeber schoolmates talking about it, the game being very popular, of course).
I therefore approached it with very high expectations, but, despite a very promising start, I stopped at level 6, I think, and I haven't come back to it ever since.
It just became too darn difficult and frustrating to be enjoyable. Those multi-stage missions are really awful, forcing you to restart over and over. The enemies can blow up your squad in a single shot before you can even see them, and the vehicle sections are especially horrible. It just ends up being more a game of luck, or a painful grind, than anything else.
Now, it could be argued that the above flaws affect the PC version in particular, while the Amiga version is superior in every way.
I was ready to believe that, but then I checked the
game page on LemonAmiga and, despite the stellar rating, some of the comments express the same kind of criticism: fun at the start but it very quickly becomes an exercise in frustration.
OK, great graphics, sounds, the humour, the anti-war message, the famous intro, "war has never been so much fun" etc. but the gameplay, in and of itself? I honestly struggle to see how it's become such a classic, and it's so affectionately remembered.
It's really a pity I hadn't the opportunity to experience it back then, as I said.
BTW I played with OpenFodder, so I don't think it's a matter of the game running too fast on modern hardware, or anything like that.
Now if anyone has some advice on how to make the game more enjoyable, I'm all ears.