I forgot about another one: RPG Maker on the PS1. I waited for months for this game to come out. There was nothing else like it on consoles in the U.S. at the time. In the runup to the game I spent countless hours drawing area maps, dungeon layouts, boss stats, everything that goes into an RPG. I had a full game ready to put together, and ideas/plans/full story outline for six more games in a series if I succeeded at designing the first one. Yeah, I was all in with this.
The game released and I spent 3 straight days on it without sleep, putting all of my notes and concepts to work. Several weeks later I reached the halfway point of the game with around 200 hours clocked on it, most of which was painstakingly entering text with a controller since the PS1 didn't have keyboard support. Yeah, seriously. I entered the script of half an RPG with a controller. So of course you know where this is going. There were two saves for RPG Maker, one was world data (maps, NPCs,dialogue, etc) and the other was scenario data (data, scripts, etc). I usually loaded both and saved both. Well, one day I was popping on there to make some quick edits to the latter, didn't load the former, saved over both. About 90% of my work was in the one that got saved over, and scripts/scenarios are useless without the world they're programmed around. After literal years of wanting to make my own RPG series, I never touched a game design tool again after that.