Today I got an email that a FFVIII speedrunner I follow had started streaming Mystic Quest with the title saying something along the lines of testing out item manipulation followed by a personal best attempt. I was intrigued at the item manipulation testing so I tuned in. He had his split times up, and his personal best was a good 14 minutes better than the world record when I last checked. Something's happened to speed things up! And that something was related to what I was going to test if I ever got around to getting over my fear of talking to the cable company and getting my upload speed fixed: buying 0 of an item.
It would seem buying 0 of an item is the same as buying 256 of an item. But it also does some weird overflow things with the rest of your inventory, especially if all 4 of your consumable item slots are already filled with other things. (There are only 4 consumables in the game so 4 slots should be enough to hold them all, but the weird overflow thing messes with that.) Buying more items after things have started breaking warps your entire inventory by adding or removing key items. The whole game is gated by locked doors, warp zones, and key item related triggers. So being able to change your inventory around on the fly allows you to skip over chunks of the game! The guy who was testing this morning went and recruited the level 31 buddy when the main character was only level 9. This buddy was able to one shot the final boss of the ice dungeon! Unfortunately a lot of the triggers can only happen once so by recruiting that character early in the game they weren't around to trigger the actual plot later on when they were supposed to. He ended up getting the game into a broken state such that he couldn't move around on the map anymore. Then he went to do a real run, but he ended up messing that up and also softlocked the game after playing for an hour.
I was intrigued to see what the world record might be now so I did some searching and it looks like it was actually broken this week. It sounds like the community only found out about the buy 0 seed bug a few days ago but have already made a route that can safely skip the entire fire area. I was annoyed watching the world record run because the guy who did it swears a lot and gets _really_ whiny and bitter when random stuff happens. I feel like if you can't handle sometimes having your party get killed then maybe you shouldn't be playing Mystic Quest.
It does make me a little sad that I knew about (at least part of) this bug but I could never bring myself to ask the people running the game about it. I wish I could talk to people.