Posts for Myria

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As of Japan's today, March 19, 2014, Super Metroid is 20 years old. It was released in Japan on March 19, 1994, according to Wikipedia. The North American release was on April 18, 1994, but it had the same ROM as the Japanese version, even using the Japanese version's "SHVC" board and chip numbers.
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Building stuff off the screen is effectively memory corruption. How far into RAM can you go with that glitch? I think it'd be nice to make a video that directly hacks the population counter by writing to the top left of the map. Quite hilarious would be building 65816 assembly code out of your city design then glitching the game into jumping to it.
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How much longer would it take to select Magna Centipede as the last level instead of Sigma? If it's only a small loss, then I think TASers should add that for the silliness factor. It's certainly not something most players of the game would expect.
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Hmm... The Breath of Fire games are good, but I don't know of any severe glitches in them that could be exploited to do a TAS. Breath of Fire 1 just has a money underflow dupe bug and a cheat code that lets you create a new save file 3/4 through the game, but not much that could be useful for a TAS.
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Is the warp stack overflow glitch powerful enough to lead to a code execution exploit along the lines of Super Mario World and Pokemon Yellow?
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I think it would be silly in videos if after beating the last X-Hunter level that you chose Magna Centipede instead of the usual Sigma one. My memory from playing this game 20 years ago is that you still end up in the final level if you choose Magna Centipede at that point. I would upload my avatar on this site, but it looks like Atma above beat me to it >.<
Post subject: Rockman ZX (DS)
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A 2D Rockman game on a system without physical entropy. =) It does use the DS time, but that can be assigned a default value. Hopefully it doesn't measure the drift between the RTC and the CPU as entropy.
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Mouse games are kind of silly to TAS because of their very wide input range. Consider Gnat Attack in Mario Paint: you could have the cursor teleport to each enemy.
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The GBA version of Zelda 3 is statically recompiled from the SNES version. It therefore has the same bugs, so there is little point. Capcom's GBA ports from SNES (Zelda 3, Breath of Fire) are statically recompiled, whereas Nintendo's ports (Super Mario World) are a new engine.
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I'm curious about something with this game. If you skip Agahnim 1 by jumping off Death Mountain, is there a glitch you can use to get the Piece of Heart underneath the lumberjacks' house? That's the only thing stopping a 100% run without beating Agahnim. (I'm not interested in this for a TAS, just actual gameplay.)
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Well, you do have to be careful in your limits. I made a saved game for MechAssault on Xbox that when loaded boots Linux. Chrono Trigger definitely has that "huge time savings" thing going for it... One of the decent exceptions would be having 8 stars already in Super Mario Bros. 2 so you can get to world A.
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I wish with Final Fantasy 6 US 1.0 that you could use Sketch to change the byte of memory that specifies whether you're in the World of Ruin. That would be a massive speed improvement =)
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(It's spelled "poll" in this case.) Poll-based recording has some advantages. Emulators that don't emulate lag correctly will work more often without desyncs, since some games won't poll the controller in lag frames. Another nice advantage of poll-based recording is that you could actually play movies on a real console by making a fake controller that counts how many times it's been polled.
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Is anything in Sonic CD random at all? CD games can easily get quite nasty by using physical entropy, but Sonic CD seems completely deterministic in gameplay. It seems that the only randomness it would have is the length of the load screens, which from the previous posts sounds like the problem. I'm just curious.
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Make Super Metroid. =) Zero Mission is interesting too, in that the game was designed for (limited) sequence breaking. They designed the game so that players could find tricks. But since it was controlled, it didn't break the game too horribly. Melissa
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Hmm. What if you luck-manipulated the random generator back to a previous internal state? It wouldn't be possible on all generators but it would work for many. It could waste a lot of time though. Melissa
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A lot of TAS work goes into luck manipulation, but I don't think it would be very easy to explain all that in the constrained time of a video. It's hard enough to explain how these old games use the controller to decide random things. Melissa
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Hmm, interesting that Tub said "he" to refer to me yet later mentioned Breath of Fire. (Myria is the evil goddess of Breath of Fire 1 and 3.) -- I think it's basically impossible to have a random generator that can't be manipulated. Final Fantasy 5 GBA is a good demonstration of this. Let's say that you're TASing FF5 GBA. You're in one area, fairly close to another area. You've just loaded a save file or quicksave (FF5 GBA bug: the encounter stream cipher gets set to a constant). You know that the bug in the game will cause you to fight the rarest monster in an area in your second battle after loading the file. With the current encounter countdown, you can get to the next area with one encounter in the current area along the way. However, the rare monster in the next area is very nasty and you don't want to fight it with your underleveled characters. The answer is obvious: fight a second fight in the current room to get an easier rare monster before proceeding to the next room. Even if you can't cause generated numbers to be consumed elsewhere (Rockman X as described above), you can change the context in which the numbers are interpreted. A potential counter to this is to give a separate stream cipher to every room in the game, but that's a lot of extra data for the save file. -- What is the significance of a take-back feature in a chess game? Melissa
Post subject: Making a TAS-proof game
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Let's say you were a developer of a game and you wanted to make it difficult to make a TAS of the game. How would you do it? Assume that you're making a longer game like an RPG or Metroid. I think the most evil thing you can do, particularly in RPGs, is initialize a stream cipher at startup with the controller entropy during the title screen, and never add entropy again. Have that be the source of random numbers for some important feature, such as the encountered monsters in an area. Save the cipher state to the save file. Although memory is the obvious problem, you could initialize several stream ciphers at once, one for each type of random number generated. This prevents manipulation by having the same random number interpreted in a different context - otherwise a TAS maker could do something dumb to "waste" that number so as to set up a good round next. Another big one is to extensively debug the movement systems at a frame level. This would have stopped a lot of the Super Metroid tricks, and skipping Celes in FF6. I would also add assertions to the game that display an error message and freeze the game if a sequence break is detected. Preventing all possible sequence breaks is difficult, so you might as well nullify the ones that occur. (Of course, this is only true if sequence breaking is not intended to be allowed.)
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Loading times are incredibly important. It's a source of physical entropy - cryptographic random number generators in most recent OS's will use tiny timing differences in drives as a source of entropy. There's no technical reason why a PSX game couldn't do the same - PSX games could be nondeterministic if they wanted. Melissa
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Okay, I dug up my description in an old email. I haven't tried this out, but I know it works - this is translated from a Japanese page Squeenix had about it. 1. You must have 1-4 party members, because the bug involves empty character slots. 2. Go to the menu screen and select Item. Use a Potion or similar item on one of your characters. 3. Go back to the menu screen and select Order. Move the character on which you used the item to one of the blank slots. 4. Go back to the item screen. The game will crash. WARNING: THIS CAN ERASE SAVE FILES. EDIT: http://media.putfile.com/FF4-Menu-Glitch
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This is impossible on SNES, because the SPC700 RAM can't be directly read back.
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Final Fantasy 6 using the Sketch bug to set the "world of ruin" flag to skip 1/4 the game, assuming it's possible =) Melissa
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FF4 GBA has a bug where if you do a certain sequence of menu operations with 4 or fewer characters the game will crash, and possibly corrupt your save files. Like sketching Gau, this might be exploitable in a big way if manipulated well. Melissa
Post subject: Incorrect statement in CV3 movie description
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Technically, this game has a really high quality soundtrack - mostly because it uses a VRC6 chip that the Nintendo of America considered too expensive to include in the game cart.
This is incorrect. When Nintendo designed the NES, they removed the ability of cartridges to connect to the sound system. Even if Konami and NoA had wanted to release Castlevania 3 with the VRC6, they could not have at that point. Melissa [EDIT by Bisqwit: Moved this post (and its replies) into the relevant topic (was originally posted as a new topic for some reason)]