Not my first computer[1], nor (intentionally) meant as a oneupmanship shot. Merely a mental milestone that somehow escaped onto the keyboard.
Back on subject, perhaps something from that age that I'd bring back is something like the Maze program (BBC Model B, randomly generated maze, run through by player in 3D[3], you having to navigate through against the machinations of patrol bots[4], a find some keys to the elevator to the next level on). Because, now I think of it, I can suddenly feel once more the far reaches of my old addiction drawing on me.
[1] I'm sure the first ("100% IBM-Compatible") PC was a 286, but before (and during) that time, there was also the BBC B, the ZX81 and the... unremembered-thing-from-a-kit[2].
[2] I know Sinclair did kits, but my memories of this thing was that it was even more basic (boot-strap/program from dip-switches, I know it could make tunes from properly set up tones), but not Altair-like. Much smaller and probably less practical. More an Educational kit, rather than a 'hobby' one, I suppose.
[3] Very basic 3D, in that your views were purely orthogonal (except for a "rotating left/right" transition effect) and so all it had to do was represent a limited number of "vanishing point" vectors and vertical/horizontal lines between them.
[4] Pasted into the above scene, probably. A scalable filled-vector representation with a small amount of windowing when emerging from/disappearing behind various walls. Actually, I'm going to write this for myself, when I have a bit of spare time. I can even remember what I had worked out about the maze-generation algorithm.
{5} But I happen to know there are people with better credentials than me, on this forum, so this is not my intention. Just me rambling, as per usual.