I mean, if I'm being honest, I think I'd have to say Oregon Trail in elementary school when they still had Apple IIs. I distinctly recall playing that a lot, which I believe was prior to getting an NES at home.
In regards to gaming at home. I had an NES before I got my first PC, so on NES, it would have to be Duck Hunt. Granted the system came with Mario Bros and Duck Hunt (with the Zapper [partial inspiration for my handle if you were wondering]) in a bundle package, but I distinctly recall playing Duck Hunt first. Then fond memories of Jaws, my fav NES game - Guerilla War, Punch-Out, Kung-Fu, Adventures at the Magic Kingdom, SMB3, just so many games it would take me a year to name them all. I'm not sure if NES games back then were significantly cheaper than the $50, now $60 (apparently moving towards $70) price tag, but my mom sure as hell went all out to make sure I had mostly every game I asked for.
As far as PC Gaming goes... Honestly I had a Packard Bell PC that had an overlay on top of Windows 95 that I don't recall what they called it, but it would make a 2008-circa Steve Jobs happy with how it was designed to replicate real-world items (ie click on a bookcase for the encyclopedia, etc). And speaking of encyclopedia, the first game I played on that PC was this game built inside Microsoft Encarta called MindMaze. I played that a whole lot and loved it a whole lot more. While I can't recall how I discovered that the "real OS" was hidden underneath that overlay, I eventually did and got into some real gaming (after also getting an upgrade with some kind of video card at some point I can't recall, might've been the first Voodoo card actually now that I'm thinking back on it).
So my first Windows 95 game was actually Spider-Man Cartoon Maker. Naturally back in '95 I was (and still am) a huge Spidey-nerd in love with the FOX Kids Animated series (which STILL holds up btw - watched on Disney+ - amazing considering the limitations placed on the writers/animators) so you can imagine what a blast I had playing that game. After that it was Die by the Sword, Monster Truck Madness, a fighting game that I think was FX Fighter, Descent, DOOM, Duke Nukem 3D. Then I got into Syndicate, Fallout, Command & Conquer, Worms, etc, So yeah, by that point I had fell in love with PC Gaming.
Not gonna lie I sometimes wish I could go back to those simpler times and be WOWed by it all. Cheers!