commodore amiga 500, when I was 5 or 6.
what was the very first thing on it that i experienced, i don't know, but some things i remember:

Cannon Fodder 2
A-Train, a game that i played for months, it utterly fascinated me and i was utterly unable to keep my company afloat, because i was utterly unable to understand how the mechanics of the materials moving around worked (i still don't, actually, but in a different way)

some Apache simulator, which took us (me and father) literally a week to figure out how to get into the actual game from the main menu stylised as a military office. it took us several days to even realize it's the menu.

the Lotus Esprit 2 game, which we played regularly.

some Airbus simulator where i took two weeks of trial and error to figure out how to take off, without manual.

some experiments with midi sequencing and notation music programs.

how every two months, dad came with a 20page long list of programs and games from some pirate seller, which we would go through, mark stuff that sounded interesting (going by name only), then he would send it by post to him, and after a week, we would go take a package from post office full of floppies, literally like 200, and the next two or three weeks, we would be trying all of it out, seeing what the things we got were about, putting the good ones on one pile, the boring ones on another (cheap floppies for use)...

ah the magical times of wonder and exploration...