Star Raiders
The first really addictive game I ever got into.
Ali Baba and the Forty Theives
First all nighter role playing game with half a dozen fellow addicts
unable to stop playing until dawn the next day.
Rescue on Fractalus!
Not too much gameplay, but ahead of its time technically.
Mercenary and Encounter
(both by Paul Woakes)
These games did the impossible of squeezing a huge fast 3-D wireframe world
into an 8-bit computer. I often wonder how on earth he managed to get it
all to reside in memory and not use disk loads.
Elite
David Braben's
epic space trading game. He managed to squeeze the entire universe into an 8-bit machine.
Way of the Exploding Fist
A brilliant early attempt at two player combat.
Sentinel
A race against the clock to solve puzzles in a 3-D world before the sentinel
caught you out. Was like some weird recurring nightmare feeling!
Leader-Board Golf
This amazingly simple ball-in-the-hole stuff proved to be a major addiction
amongst a load of my late night drinking friends for weeks on end.
Tetris
So addictive that you ended up dreaming about falling blocks.
Populous
I had roughly sketched out a spec for a similar idea whilst doing Snooker/Pool,
but Peter Molyneux's implementation was excellent.
The Secret of Monkey Island
I remember a load of us playing this for a whole weekend. It was enhanced by
the use of a fancy Roland sound card with stunning music and effects.
DOOM
'Nuff said.
Duke Nukem 3D
Overkill on the doom-esque 3-D and humor bunged in for good measure.
Quake
Didn't have quite the same fresh appeal as "DOOM" did, but brilliant nonetheless.