Note - my mentality/play style is to play games "slow but sure"; making sure if I got somewhere in the game once, I could do it again and again. Although I found it exciting to get somewhere in a game by luck/skill, I wasn't comfortable with it. Also, I wanted to get and keep the best stuff in the game, and not use it up in case I'd be stuck later. This attitude was the main factor for me deciding if a game was "good" or not.
Assassin (Special Edition) - Great graphics, good challenge and scoring system, big levels with lots of exploring to do
Frontier - I spent a long time on this game, though I was never too good at it. My afore-mentioned attitude meant I always worked my way up to the Panther Clipper then hoarded money and the best equipment and crew. I never got anywhere with the military/spy missions
Chaos Engine - Excellent, but I wasn't too good at it. I always tried to kill all the enemies... maybe I should have tried running more?
Alien Breed - Same as Chaos Engine! But harder. I seem to remember the aliens being that fast that there weren't many opportunities to run safely?
Jurassic Park - The raptor bits really, really scared me.
Oscar - We got this with the 1200. Very well produced game, though the gameplay itself was lacking
Space Hulk - An excellent game spoilt by my attitude. I couldn't get anywhere because I always tried to find map points where I could position my marines then forget about them. Then again... I seem to remember hunting online, and not being able to find any guides, FAQs, or in fact any indication that anyone had ever got far in this game?
Desert Strike - The title music = win. I remember the name of the guy who made it... Jason A.S. Whitely I think. He also did music for Space Hulk.