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Tool-assisted game movies
When human skills are just not enough

Submission #4564: DaJaWi's GBA Harry Potter and the Sorcerer's Stone in 56:17.96

Console: Game Boy Advance
Game name: Harry Potter and the Sorcerer's Stone
Game version: USA/Europe
ROM filename: Harry Potter and the Sorcerer's Stone (USA, Europe) (En,Fr,De,Es,It,Nl,Pt,Sv,No,Da).gba
Branch:
Emulator: BizHawk 1.9.0
Movie length: 56:17.96
FrameCount: 201757
Re-record count: 32617
Author's real name: David Wigram
Author's nickname: DaJaWi
Submitter: DaJaWi
Submitted at: 2015-01-22 02:21:39
Text last edited at: 2015-02-02 00:04:16
Text last edited by: Spikestuff
Download: Download (20394 bytes)
Status: published
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Author's comments and explanations:

Harry Potter and the Sorcerer's Stone

Just to be clear, this is the GBA version which is distinct from the RPG GBC version, the action/puzzle PC version, the adventure Playstation version, or the more recent PS2, XBox and Gamecube version. (So many versions!)

This is more of a puzzle/adventure game. It's very unforgiving for a real-time speedrun, so it was a game that I'd always wanted to see a TAS of. It was only recently that I realised I could be the one to make that happen!

About this Run:

  • Aims to reach the end in fastest time
  • Takes damage to save time
  • Manipulates luck (the spawn points and directions of gnomes, specifically)
  • Made originally in BizHawk 1.8.3, but due to the GBA input fix I've resynced it to run on BizHawk 1.9.0+

Suggested Screenshot: 89160


As this is a fairly slow paced game I've added some commentary in the form of subtitles to make the run more interesting and to explain the tricks, many of which are not immediately obvious. For those of you who prefer your TASes unadulterated, I have an alternate video without commentary.


(Link to video)

The commentary subtitles are available in .srt format here. (Password - 'tasvideos')


General Comments

I have a tendency to ramble on for far too long, but rather than repeat what I put in the commentary I'll just list the main factors to TASing this game.

Movement: When moving, each step takes Harry two pixels (or one pixel diagonally). This means if you need to move exactly one pixel in any direction, there is no easy way to do this. (Think of it as like being confined to one colour of squares on a chessboard). If you absolutely have to move just one pixel it can be done most easily by brushing against a wall as you turn a corner. There are only a couple of places in the run where the alignment was really important, one being to get between the thorn bushes at the start of the Forbidden Forest.

Spells: Casting a spell takes a long time (48 frames), to the extent that it's quicker to both take damage (12 frames) and pick up some health (33 frames) than it is to kill an enemy. The result is that taking damage and using invincibility to get through enemies happens a lot in the run. When I do have to use a spell, using it moves you a few pixels in the direction you are facing, so trying to only use spells when facing directions you need to travel saves a bit of time.

Gnome Manipulation: Most enemies either move according to a pattern or just chase you, but gnomes are different. Once spawned they cannot easily be manipulated, but when they first spawn their exact position and direction they are facing is according to RNG. A crucial part to TASing this game is to manipulate the RNG so that they will spawn in a way where they will not obstruct your movement.

The easiest way to manipulate the seed is by swapping spells (this also doesn't lose any time), however this only works when you have more than one spell to swap between. Therefore, at the start of the run before getting Alohomora I have to find other ways to manipulate the gnomes.

Room Transitions: While the room is fading out during a transition, if you hold a direction you will begin the next room standing one step in that direction. This obviously saves a couple of frames during every transition, but in a couple of places it can be used to avoid certain triggers, one of the biggest being to avoid the save book in the phial puzzle level at the very end of the run.

Hitbox Extending: Harry's hitbox can be made larger in two ways. When you cast a spell, his hitbox is a lot larger. This means you have to be careful not to hit enemies because of it, but it also means that if you ever need to cast a spell near an item (as I do in the flipendo challenge near the beginning) then you can collect the item with the spell hitbox and therefore walk fewer steps towards it.

This is obviously very situational since it only works if you needed to cast a spell anyway, but once you get the flute there is a more consistent way to extend Harry's hitbox horizontally, just by playing it. It doesn't increase the hitbox by as much as a spell, but can still be used to collect items with fewer steps. It can also be used to hit some triggers early, including certain horizontal room transitions. This is possibly my favourite trick in the game, just because I never would have considered that the flute would be one of the most recurringly used items.


Level Comments

Again, most of the level comments can be found in my video commentary above, so I'll only mention the few things that I couldn't fit.

Potions: In the far bottom right corner, when returning from collecting the phial in a jar, I take one step up-right away from the bookcase to avoid rummaging through it.

Hagrid's Garden: To roll the eggs in unintended directions, walk up into the gap between them and an adjacent hedge, then stop moving. If you position yourself just right, you will clip slightly into the hedge. You can then turn towards the egg and roll it away from the hedge. There are three switches you are supposed to press with eggs to get across to collect dittany. This trick allows me to only press the bottom two switches. The minimum required would be to only press the bottom switch, but I cannot find any way to press just that switch that doesn't take longer. As an aside, I'm so glad the garden can be skipped this way, because the rest contains tonnes of gnomes, and without two spells it is very hard to manipulate them at this point.

Flying Practice: In all flying sections the controls are a little awkward. It's possible to swap to a more smooth flying style, but the options menu takes so long to open that it isn't worth it. With TAS precision it's also very possible to overtake what you are chasing, whether that is the snitch or in this case Malfoy. Once you have collected enough boosts to fill the bar, you no longer need to control the broom and just have to time the catch correctly. During this autopilot, the game keeps moving you towards your target, but if you have just overtaken them then it gets confused and turns you round in completely the wrong direction.

Alohomora: Uninteresting gameplay wise, but a life-saver in a TAS since now that I have two spells the gnomes can all be manipulated more easily.

Sneaking to the Trophy Room: Bypassing the prefects is the biggest skip in the game. It's only possible with diagonal movement, as orthogonal movement (or any change of direction once in range) will cause them to stop you. They do detect you, hence them stopping and facing you, but as long as you walk right up to them without changing direction they will not actually stop you. You then need to nudge past them until they turn around, and at that point their detection resets, so you can change direction safely before they re-spot you. To get away, you then also have to move diagonally away from them until you exit their detection zone. For the first prefect I have to walk away to the left, because there wouldn't have been enough space to get out to the bottom right while still walking diagonally, and as I said before, changing direction makes them stop you.

Greenhouse: Funny story, I TASed the entire greenhouse up to the last flower only to discover I was missing one, because I had forgotten to collect the one in the bookcase in the beginning. Eurgh...

Avifors Challenge: I show off a graphical glitch here where you can make one spell have the colours of another. It works by casting spell A normally, then swapping to spell B and casting it into a wall so that the spell projectile never actually appears. Then when you next cast spell B it will have the colour of spell A.

Path to the Mirror of Erised: (This is the level on the fifth floor after escaping from Snape's storeroom.) There's a platform cycle when you first go to the room in the top right corner that you miss by only a few frames, but I cannot find any way to make up that time. If it could be done however, then there would be more time that could be saved later. When you reach the avifors switch (after using the 'return platform' - at ~35mins in the video above) I currently hit it on the earliest possible frame. This triggers the platforms in the left room that are crossed later to reach the exit. Because you have to wait for a while for the platform to come back however, you can activate the avifors switch whenever you like during that time, and that will determine the spacing of the platforms when you reach them later.

After much experimentation it turned out that hitting the switch as early as possible was actually best (which seems a little anticlimactic), but if it was possible to get to the switch any earlier then there would be some better timings to hit it that would make the platforms on the left be in a better pattern when you reach them.

Wingardium Leviosa Challenge: The exact movements and timings required to optimise using Wingardium Leviosa are pretty complex, so rather than explain them here I'll link to a forum post where I explained it in more detail.

The Library: What a joke of a level.

The Forbidden Forest: When I played this game as a kid, I always remembered the escape from the forest as being this really huge maze that took ages, but it turns out there's a really quick path if you know which way to go.

Devil's Snare: This is an odd level, because so much of it is pointless, even if you were doing 100%. I wonder if at some point in development you needed to destroy all of the plants to exit, as opposed to just the one by Ron and Hermione. If so, I wonder why they changed it? That would certainly be lot more interesting.

Quirrell: The glitch I use to get zero health is not at all beneficial, as taking damage will still kill you, but I thought I'd show it off anyway. In the second stage of the battle, in order to 'two-cycle' Quirrell you need to hit him four times each cycle. This is difficult because he normally swaps sides after every two hits. Getting a third hit is not difficult, because if he had been about to cast a spell when the second spell hits him then he will still cast one more, but to get four hits takes more work. You need to make sure there are two spell in the air at once when the second shot hits him, so that he then gets hit a third time before casting the fourth spell.

It's also pretty tricky to get the spells to actually hit the mirror, but since 'tricky' is part of the fun I decided to keep the rocks chasing me for the entire battle to add to the excitement :P


Known Improvements:

Over a fairly long run like this it is inevitable that there will be small improvements found for earlier sections while the run is being made. These both save so little time that it was decided that it wouldn't be worth redoing everything until a bigger time-saver was found as well.

  • The first time I go to Hagrid's hut I took damage from the thorn bush so that I could use invincibility to get right up to it as I destroyed it. I later discovered, once I had a greater understanding of Harry's hitbox, that it is possible to space out your spells in such a way that you can get through without taking damage. You can see this later in the run the next time I go to Hagrid's hut. It would save ~14 frames to do it the first time.
  • I realised part-way through the run that I had been wasting one frame on some of the dialogue boxes up to that point. At some point I started mis-timing the button press that closes the dialogue box, so for a chunk of the run each time there is a conversation, the first dialogue box in the conversation could be closed one frame quicker. Since it was only the first textbox each time, and only for part of the run, this only adds up to about 30 frames maximum.


Acknowledgements

This was the very first TAS I started working on, so it was invaluable to know that there were others interested in it otherwise I may well have lost motivation. So thanks to anyone who either read my rambly comments in the forum or watched my WIPs here and on youtube, and also those who commented in the forum thread, either with suggestions or just with messages of encouragement.

More specifically, thanks to jlun2 for letting me know the stealth sections could be thoroughly broken, to solarplex for repeatedly encoding my WIPs when I was too lazy to do it myself, and to AKheon for pointing out a ton of tricks, including many cool glitches that unfortunately didn't save any time and so never made it into the run. Maybe one day some new tricks will be found that enable some of those glitches to be used.

And I guess thanks to you for watching.


Mothrayas: Judging.

Mothrayas: The game seems a bit slow paced at times, but has been received well regardless. Accepting for Moons.

Spikestuff: Publishing


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