Can a mod please delete my previous post as I cocked it up? Thank you
I didn't have a PC until Windows 95 was a thing, so never really got to experience the horror of DOS, instead I grew up with an Amstrad CPC464 in about 1987 - taught myself some programming at 7 because I was a weirdo - and an Atari ST in 1989 (was making games in about 92 as I got the hang of STOS) - the latter was a really formative experience for me, an amazing computer that could do so much. Highlights for me:
Honourable mention for Geoff Crammond's F1GP, which someone else already mentioned - started a long love affair with racing sims (probably also pushed along by the wonderful arcade games that came with my ST, Outrun and Super Hang On), which has led to me getting a VR setup with wheel and pedals to race in Assetto Corsa, iRacing and RFactor 2). Another for Sim City original version. No later version grabbed me in the same way, the pure fucking addiction of that game was amazing.
F19 Stealth Fighter
Flight sims didn't usually do much for me, but this one grabbed my by the bollocks. Brilliantly addictive, the 3D was decent enough, the enemies were dumb enough to have some fun with and the between-mission screens were beautifully drawn and animated. The huge box, the enormous manual which contained so much extra information that you didn't really need but added wonderful flavour to it.. I miss those days.
Midwinter 2
Another amazing Microprose classic. Another huge box, another wonderful manual, a silly mini novel, brilliant 3D though I now find the controls more or less unworkable and can't quite fathom how 11-year-old me played the game, that trademark Microprose gorgeous pixel art between missions, complex missions in an open world where you could go anywhere and do anything. Such an incredible game.
Damocles (Mercenary 2)
Occupies a similar place in my heart to Midwinter 2, albeit this is a little earlier, and a little more British. The ship's computer was hilarious, the references to Maggie Thatcher thoroughly on point, a whole solar system to explore where you could do anything you wanted, even after the comet hit the planet and in theory you'd failed. Stunning game.
Operation Stealth
The first adventure game to really grab me, a wonderful rip off of James Bond films, with all the tropes, gorgeous to look at and while suffering some dodgy translations (it was a French game by Delphine who would go on to make Cruise For A Corpse [a game I wanted to love but could never get into], Another World and Flashback, and who had previously made Future Wars).
Nebulus (aka Tower Toppler)
Came with my Atari ST and it was an absolute bastard. Seriously bastard hard. This game caused me no end of ballache.
Mad Professor Mariarti
I spent hours on this as a kid, puzzling through the 5 levels of weirdness. Tbh the collision detection was utter shite, there was no scrolling (it was flip-screen) but there was some inescapable charm.