Tough call...
First one to come to mind is ad-venture capitalist. But that's just a simulator with numbers going up. It's simple and stupid, but strangely addictive (read: it's a psychological trap)...but that had no real technical issues
C&C tiberian sun was my largest letdown. Anticipated it for at least a year, but red alert was just better all around.
Hidden & dangerous (first one) was my most buggy game. And that's BY FAR. At one point I had to make a detour because the road I initially cleared (and most obvious one) just made you fall through the map. Which was something that happened often, btw. I also remember things like "if you save when your troops are crouched and then reload, they float", all sorts of crashes and plenty of weird gimmicks.
Then...from the bottom of my "played on steam list"...
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Kairo was just someone playing around with an unreal editor. Reading my review for it again I was far too mild (this was one of my first negative reviews).[/URL]
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Everything was just stupid. There's artsy, there's wannabe-artsy and then there's this piece. Perhaps it could've gone for a cultural thing if the programmers had bothered to create some standard walking animations instead of "bouncing around" everywhere
* 1993: space marine gets special mentioning: it's a bog standard R-type game that I found boring (so I gave up within an hour). Not specifically bad...
but then the author pops in and tells me my opinion is wrong. I never responded (I believe that bad publicity beats no publicity...and I'd rather want no publicity about it), but ey...he at least makes THIS list