Experienced Forum User, Published Author, Active player
(256)
Joined: 11/16/2020
Posts: 10
Fortranm wrote:
Amazing find! Have you checked the Classic NES release on GBA by chance?
Ah, no I haven't! I have checked the US PRG1, US PRG1, PAL, JP FC versions in terms of cart releases. None of them seemed to have an accessible screen that allowed execution to jump to RAM from what I saw.
Experienced Forum User, Published Author, Active player
(256)
Joined: 11/16/2020
Posts: 10
Link to video
I have now found a Credits Warp setup that officially saves time. The above video is an unoptimized demonstration for the sake of showing this is possible.
The initial RAM area in which the Program Counter jumps is the same as the previous setup ($179C). However, instead of using save data and controller inputs to execute the payload, "High Score" ($17F8-$17FA) is used to jump towards Object X Coordinate memory (which starts at $038C). Then, a few objects are carefully manipulated for their X positions to jump to the credits.
However, the score has a notable limitation. It is stored in decimal format, meaning any opcodes or operands that contain letters are unavailable. On top of that, the first byte will never having a units digit different from 0. This makes the JMP opcode not possible (0x4C or 0x6C), however JSR is still available (0x20). This will make the Program Counter eventually return to $17FB, so "Current Score" ($17FC-$17FE) also has to be used to RTS back to safety.
The route is the following:
- Start the run by naming the second file to ....... - very important to use the second file to align the Program Counter properly. Also don't name any other file. The purpose of this is to simply allow the Program Counter to get past the save data without causing anything disruptive.
- Start the run and achieve a score of 038820 in level 4. Other slightly different scores might work too.
- Game over. This will allow the High Score to permanently hold 20 88 03.
- Collect 5800 points. A damage boost at the end will be needed to access the glitch screen which will award 200 more points, the objective is to have 6000 points by the end of Stage 10. The demonstration above collects the Holy Water to perform combos on enemies for extra points.
- Go back to the starting area and destroy a candle in a pixel-perfect spot to write X coordinate 0x52 at $38F. I think this is the X coordinate of the sparkle effect.
- Go further back and jump-whip in a pixel-perfect spot while facing left to write X coordinate 0x4C at $38E. It is important to whip in such a way that the animation finishes before landing so that $530 (some kind of property of Simon that advances by 0x24 any time he moves) will have a 0x01 written to it and contain values of 4n+1, which will come into play later. Also note that after this point, no attacks should be performed again, or else this memory value will change.
- Move to the area around the last moving platform and aim to have a splash animation object to despawn at a pixel-perfect spot to write X coordinate 0x79 at $0390.
- Move to the ending area and damage boost up to the top platform. This should set the score to 006000 and create the requirements to access Stage 11, Substage 255.
- If necessary, wiggle around a bit so that when you touch the stage exit, $530 is exactly 0x71.
- Make sure to touch the exit at the right time so that the area around $7C9-$7CF doesn't contain anything harmful to the setup (PLA, STP for example). This seems to change depending on the frame the exit is taken.
- Win.
This setup will allow execution to eventually get to $17F8, where a JSR $0388 will be performed. There, the following code will be executed:
BRK
BRK
RLA ($3C,x)
JMP $7952 -- jump to routine that starts the credits sequence
After the routine at $7952, execution will eventually return to $17FB, where after a BRK, the Current Score will RTS and allow the credits to start properly.
This setup can probably be better, but at least this officially makes it faster than any runs that have existed so far.
EDIT: input file - User movie #638512374616987382
Experienced Forum User, Published Author, Active player
(256)
Joined: 11/16/2020
Posts: 10
I have found a Credits Warp in the Famicom Disk System 1.0 version. This method however takes roughly 2 hours to set up, so it's not currently a faster way to beat the game.
Link to video
Full explanation in this pastebin: https://pastebin.com/75tbpnLJ
tl;dr: The glitch screen accessible by damage boosting up to the stage exit in Stage 10 contains a spawner with an invalid index that ends up making the game execute code from RAM. A payload can be prepared to warp to the credits (though with some limitations).
I haven't been super rigorous in my research, but I have not found an accessible screen with potential for RAM execution in any of the cartridge releases.
Input file: User movie #638511647302356536
Experienced Forum User, Published Author, Active player
(256)
Joined: 11/16/2020
Posts: 10
Very nicely done, that Dracula fight in particular is just amazing. It's great to see an application of the scroll glitch in this game and in this branch.
Experienced Forum User, Published Author, Active player
(256)
Joined: 11/16/2020
Posts: 10
Absolutely incredible work. There has clearly been a lot of effort that went into making this TAS. It's particularly mind boggling to me just how different this new TAS is from the previous one. For a game like Castlevania, I find that pretty incredible.
Experienced Forum User, Published Author, Active player
(256)
Joined: 11/16/2020
Posts: 10
I have a very important message.
This is a 1 frame improvement. I took out a roll on a nest during the last monkey puzzle of level 2, which was done for lag optimization, but by readjusting the jump onto the rhino later on I managed to reduce that lag anyway.
Now, this is a very important frame. It is not just any frame: it brought the time down to 11:22.995, which is down from 11:23.012 of the previous movie. I am a big fan of breaking second barriers. I find it cathartic.
So yeah, please replace the input file with this one, thank you :) - https://tasvideos.org/UserFiles/Info/637892577217703830
Experienced Forum User, Published Author, Active player
(256)
Joined: 11/16/2020
Posts: 10
Hey, sorry for the wait but I think this was worth it.
When I had delayed this submission to update it with the faster 2-1 skip, I decided to scan this site's forum thread on the game one more time to make sure I didn't miss any piece of info, as I remembered there was a lot of information there. Lo and behold, I found out that there was a more recent TAS sketch by Dooty and r57shell than the one I had been using as a reference, which included a few more skips I wasn't even aware of! I was pretty shocked to see it, no idea how I missed it all this time. Anyway, as such I decided to remake this movie from scratch and it now includes a lot of major and minor improvements. The total time saved over the previous version is 2798 frames. Full details in the updated movie description.
Here's the new input file: http://tasvideos.org/userfiles/info/67964059555447336
Experienced Forum User, Published Author, Active player
(256)
Joined: 11/16/2020
Posts: 10
I'm glad you enjoyed it Tompa :) yeah in level 6 you can't shoot diagonally or downwards either. You can't shoot diagonally in mid air on normal stages either, for that matter. The water mechanics act somewhat similar to being in mid air in a normal stage from what I could tell. Either way, if diagonal shots were possible it probably would've made this level even harder to optimize lol.