Hello!
I was wondering if anyone had any interest in running this game. I'd like to see a run of this created (even though the game seems pretty linear), but I don't know if I'll be the one to do it or not. I have very little TASing experience, not to mention a lack of motivation for a project like this.
Despite that, I've been doing some research into it the past few days, and came across a couple of significant discoveries that help break the game somewhat, though admittedly, not as broken as I'd like. Unfortunately, it seems as though the majority of grinding is still currently necessary for the various bosses, the end result being level 28 by Guruda/Eldeel (31 is the max for this game). Anyway, in case someone else would like to work on this, here are the discoveries.
This first one I hope will prove useful someday, but so far it is still a mystery (and a currently unimportant one at that). I've noticed that when wandering around the Border Ridge, I'm occasionally able to damage the bees at level 1 without a weapon, which I believe is supposed to be impossible at that point. I can't say for certain, but it seemed to happen when trying to attack them right against a wall. Anyway, I'm curious to know if this behaviour could possibly be replicated against bosses under-leveled, and if so, how. As it is, the first two bosses require level 4/5 (with the appropriate equipment, of course), but the next noteable boss (Gadis) requires level 15, Bami is level 26, and as mentioned earlier, Guruda and Eldeel are level 28. That's quite a level spike, so if the grinding could possibly be reduced somehow, it could be quite a time-saver.
The next glitch involves using the Mirror Necklace (can be bought for 8,000 G in Komodo or Lance). Normally, the game doesn't let you use it while fighting bosses. However, if you use it right before initiating a boss battle, the boss will temporarily be frozen in their opening animation; how long depends on how quickly you can get through the pre-boss stuff (some bosses have dialogue before the fight, which I think eats up the stun time). For some bosses, this means you can get free hits, others not. By far the most useful boss to do this for is Eldeel. Normally, he's got all those plot mechanics before he can be damaged, but using the Mirror Necklace beforehand freezes him temporarily, and unlike some bosses, he is immediately vulnerable. This is the case even with the Radiance Sword equipped (he normally can only be damaged by the Hero Sword, excluding "magic" attacks), and if you're fast enough, you can kill him before he even has a chance to do anything. However, when I tested this at level 28, I was not able to do quite enough damage before time ran out, even making use of the misalignment glitch (detailed below). Levels 29 and above you can kill him in time with the Radiance Sword, unfortunately the transition from level 28 to 29 is another 11,000 EXP, probably too time consuming to be of use. I've tested this with the English patch, and am hoping the Japanese text scrolls fast enough to give a little more time to damage him. If not, that means that upon using the Radiance Necklace, he'll immediately go to his armored form, which should still be a good time-saver.
This next glitch involves getting Adol misaligned slightly, which allows a few "necessary" events to be skipped. To do this, you need to either use the Wing or a healing item when transitioning to another space. If timed correctly, Adol's position will be on part of a space that he normally shouldn't be on, which allows him to pass certain triggers. As far as I can tell, you can't get fully out of bounds via this method, just partially. Even then, it's somewhat restricted, since when you move vertically, it seems that you can only clip (partially) through objects on Adol's right, not the left (as far as I can tell). Also, this is a pretty easy bug to correct; you simply bump into something "normally" (by pulling away a litte and running into it again), and your position should go back to normal.
From my testing, it only seems to actually skip a few things, but some of those instances are really helpful. One such instance is seeing the Sage of Celceta in Selrei without the three Eyes. However, this has the drawback of needing to get to Minea later, so the Golden Pedestal can be bought from Pim (needed to get to the ancient city part of the game). Theoretically, you can see him on your first visit to Selrei, however, doing it this way means that the trigger to get to Minea never shows up (as far as I can tell). Instead, it seems that the best time to use this glitch is anytime after you talk to the elder via Flair's help (after giving Gazok the Celceta Flower).
You can also use this glitch to see Lefance without the Hero Sword. You still need to talk to the Sage first (again, not too early), but afterwards, the game will let you clip on through him, provided your vertical position is misaligned and you immediately hold left. I believe this means that one could complete the game without ever obtaining the Hero Sword, though the Ice Sword would probably be needed to have enough STR to kill Bami. However, I think that'd require level 30/31 (max) to get the needed STR. (I should also note, walking through characters after talking to them is not uncommon in this game, but this instance has Adol taking a couple steps away after the conversation. This would normally be enough to prevent clipping through someone, but for some reason, being misaligned helps in this case.)
Other known instances where misalignment is useful is when you first enter Komodo, Karna takes you to the elder, she normally stops you if you try to exit his house without talking him. Exiting the house at a misaligned horizontal angle means you can avoid speaking to him.
In the Minea Plains, the game ordinarily makes you fight that one boss (the centaur?) before continuing to Zeptic/Lance, but you can use horizontal misalignment to clip through part of the bridge to avoid fighting him.
Lastly, in the Temple of the Sun, you're supposed to talk with Lefance's 5 companions briefly, but using vertical misalignment means the event won't trigger.
There's also using vertical misalignment before fighting Eldeel to actually go up and speak to him, though it's unclear if the dialogue is his, or someone else's (it's not in purple color, and he only says it once). In the English translation patch, he says "Ah, Adol. It's good to see you alive and well. Please, have a seat." This could potentially be useful to trigger the final fight a little further up, and thus, have a little extra time to hit him after using the Mirror Necklace.
There are several other useful instances I had hoped this would work for, but these are the only ones I know of. A couple of failed examples are clipping through the dog in Highland (before talking to Leeza), and passing through the rock piles at the Temple of the Earth. There's more than that I've tried, but I can't think of them right now.
The last known glitch is using enemy knockback to avoid triggering the scene where Adol gets struck by lightning and ends up in the Stormvale Castle. So far, this is the only known application of this glitch, but it's a nice time-saver, since you can immediately go to the Mountain of Ice. I don't think it matters, but it doesn't seem possible to do it when heading south, just north. Sometime, I'll have to try activating the scene at max level with the Radiance Sword, and see if Gadis, Bami, and Guruda can be killed in that one castle scene.
So, that's about all the useful info I have (if anyone wants, I can post info about the route/minimum levels to damage enemies/bosses). Does anyone else have any more information or ideas? Is anyone even interested in seeing a run of this game?
EDIT: Oh, right. Some movie files might help with a couple of the glitches. Game is "Ys IV - Mask of the Sun (J).smc", played on Snes9x v1.51
EDIT 2: Dehacked giving corrupt file links, so uploading to Mediafire.
EDIT 3: Links dead, but both examples can be seen in the WIP in the post below.