I don't mean games that aged badly. I mean you were just stuck with magazine articles and screenshots, or maybe at best looking at the older kids at the gaming clubs. For me there were 3 games with varying levels of disappointment:
Dungeon Keeper - least disappointing. I guess there's no surprise here. I mean it's a Molyneux game, it designed to hype you up. I never saw any gameplay, just a magazine review. I don't remember what it was like in my head, but on paper this game seemed awesome.
When I finally played it as an adult it was okay, it was interesting and I was actually impressed with the graphics and level of interaction. It's just that once you've unlocked all the buildings every mission is the same.
Silver - average disappointment. I hadn't seen reviews and I did actually start it once but couldn't get past the tutorial (I was an idiot kid and I was just starting out with PC gaming). But I liked that it was 3D, which was still something very new and combined with the prerendered backgrounds it looked great! Plus there's the name, it was always a mystery to me. Silver... like I know what it means (English isn't my first language) but why is it called that? Is it the name of the hero? Or... is he looking for a silver sword or something?
A few years back I played. Ugh, the camera is too far away in some scenes and combined with the low poly models it's impossible to distinguish between my party members. The controls were disgusting and the game was grindy, repetitive, not much really going on. I dropped it after 1/4 or something, so I gave it a fair shot.
Arcanum - most disappointing. Mostly the Silver level of familiarity - no reviews, very little play time, but I couldn't get a handle on the mechanics. But I was drooling over the game when I watched some older folk play it. A half-ogre in a suit, a pistol wielding knight in armor? All in a Victorian setting with both tech and magic! Sign me up!
But it's a Tim Cain game... I've tried it like twice over the years and the first time I spent a good maybe 7-8 hours and I ended up cornered and ambushed in Drog Black Tooth's cave who was like level 30+ and none of my party members had reached 10, I think. After years I tried it again, this time I softlocked even sooner. This game can suck both my balls! I finally at least watched a storythrough to know what it's about, I've watched the entire Tim Cain playlist about Arcanum, it's a very ambitious RPG, I wish there were more like it... just not balanced by Tim Cain.