I think it was Bomberman on consoles, i wasn't even aware i was using cheats, my character just stopped exploding. Must have been some sequence of buttons i accidentally pressed or moving my character through something that it activated. No clue. GTA Vice City is a game i used cheats on after searching for them online.
I remember the first trainer i used and it was for Project I.G.I. Felt so much better than using any cheats and i preferred using trainers over typing cheats after that.
Syphon Filter 1 for the Playstation One with the button combination cheats - all weapons & Inf Ammo / Level Select / Super Agent. Then came across the ol' action replay and branched off to other PS1 games, good times.
I think it was Sim's Busting Out. I did not remember what I did, but then suddenly there's a gnome in the lawn that I can click 'fill all motives'. Made the career progression much easier. Right after that day, I've been searching the proper cheat but whatever button combination I did, I could not get the 'fill all motives' at all. Gave up after that.
Probably GameShark for Game Boy but I don't have very many memories of that.
I remember having so much fun with friends playing on PSP custom firmware & cheating on SOCOM Fireteam Bravo 2. I felt like every lobby had a few cheaters and you had to outdo them
Other than that, I probably started using CE on flash games from AddictingGames, Miniclip, ArmorGames, etc.
the very first game i cheated on with cheat codes, Grand theft auto 2, top down game on PS1
the very first code editing type thing i ever cheated on was either a pokemon game, for dem masterballs, or a nintendo ds game called Spectrobes, i memorized all the little cards that i could find online *you had to have the card and it would have holes in it to tap certain spots on a redemption screen* but i couldnt find the things i needed to feed them so i gave myself 99 of everything. And that is when I became fascinated with coding/computers
From there it led to Modded Xboxes, emulators to play games from my childhood i couldnt find anymore, so on and so forth
If we're talking game tampering then it was Disgaea 2 on the PS2 using an Action Replay. If we're talking like exploits and stuff then it would've been Pokemon Silver.
Pokemon Red, the emulator has a "cheat search" function, the simplest form of cheat engine , which I believe, is still there after all these years. A simple edit to the static address and we called it a day .