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Thread: Altered Beast Rom Hacking

  1. #1
    Toejam is a wiener. Master of Shinobi SEGA-Jorge's Avatar
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    Default Altered Beast Rom Hacking

    Hi! As many of you know, I am a really big fan of Altered Beast. It is actually one of my favorite games on the console. I've really grown to appreciate and enjoy the nuances that are in the home port, and in many ways, I feel each version (arcade and Megadrive) have really great aspects about them that keep me coming back. After seeing all the great stuff that has been done within the rom hacking community with this game, I think it would be awesome to add a couple things to the Genesis port. I am totally new to rom hacking but I some general questions: I am looking into what it would take to add some changes to Altered Beast. The changes I'm looking to attempt are as follows...

    - Increase amount of hits enemies take based on difficulty. (for example: having the zombies in round 1 take 3 hits instead of 2 hits, and grave masters taking 4 hits instead of 2)
    - Having enemies take more hits on certain rounds. (Example: base zombie takes more hits in round 4 than in round one (like the arcade))
    - I'd love this to be tied to the difficulty. Normal should stay just as it is, but Hard and Hardest settings should have enemy hit points that more closely resemble their arcade counterparts.

    I imagine this would all be done with a hex editor, as the values for health could be multiplied for certain enemies by 2 or 3 based on difficulty. I'm certain it is much harder/more involved than this, but I'm hoping there is some sort of global variable mapped for this kind of thing that was used for tweaking during debugging/testing.

    Rom Mapping/things I should be looking for in the code/hex, suggestions, or comments will all be incredibly helpful.

    Any assistance/advice is greatly appreciated. I really think that this version of Altered Beast could use some small touches to the enemy health/difficulty which would really go a long way to completing the arcade feel. I think that the Arcade version's hard and hardest difficulties really make the game play shine, and although I don't suspect that all the enemy behaviors and nuances can be replicated, (outside of some serious ASM hacking) I think bumping hit point values at the tougher difficulties will really help to round out the game.

    Thanks, I look forward to your comments and suggestions!

    -Jorge!

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    It's very likely you'll need to know some asm to understand the logic of the thing.

    To locate interesting data, you may look at RAM watcher in Gens for example. If you know the ennemy can stand 3 hits, you watch all RAMs location with a 3 inside. Then you knock it once, and you watch all previous RAMs location that are now 2, etc. If you're lucky and hits are computed in this simple way (could be the opposite : 0 to 3, or something totally different).

    Then you'll have to find how the 3 was originally written at this pos. This will likely require asm knowledge.

  3. #3
    Hedgehog-in-Training Hedgehog-in-TrainingNameless One Manveru's Avatar
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    Interesting idea. I have the same idea with that game, but i want to fully program the port from Arcade Altered beast to Mega drive. My problem? i can't find any software to rip sprites and backgrounds from that arcade with fulll accuracy.
    I fell in love with Mega drive in 1991. Now programing for it...

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    Mame has a tile and tile map editor that can help. But not always... What I did for Shinobi is capturing a movie of a play through with mame in mng format (not destructive) then remove background with paint.net. It's easy with games of the era because they don't use the same colors for backgrounds and sprites.

    Did you check the sprites resources ?

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    Hedgehog-in-Training Hedgehog-in-TrainingNameless One Manveru's Avatar
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    I found a guide with an app to rip graphics, but i found it a bit difficult (it was a few years ago but i can't find it now). Capturing video or images and remove things is the way to do it, but i want to avoid that because it is a bit boring and long to do. Mame sadly does not work with Altered beast...

    Sprite resources and other just have a few sprites but no all, and no backgrounds, but trying to find the web i said before, i found that web with the backgrounds: http://vgmaps.com/Atlas/Arcade/. It has both planes fused, but it is a great help to begin. Sprites would be harder to get, i will try to find the web i was talking about.
    I fell in love with Mega drive in 1991. Now programing for it...

  6. #6
    Master of Shinobi
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    If it was easy to reuse the arcade sprites in the port, is rom space the only reason Sega didn't do it in the first place?

    Boy I wish 32 meg ports of Golden Axe and the likes

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    Hedgehog-in-Training Hedgehog-in-TrainingNameless One Manveru's Avatar
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    I have been looking for the ripping stuff, and i see MAME can rip backgrounds, and some tiles like fonts and so, but sprites seems to have their tiles disordered somehow, and it can not be ripped easily. I tried this app: http://reassembler.blogspot.com.es/2...te-viewer.html but it does not work for me. Probably capturing the sprites and cleaning the image should be the only way to get them, except if some of you has a better idea...
    I fell in love with Mega drive in 1991. Now programing for it...

  8. #8
    Toejam is a wiener. Master of Shinobi SEGA-Jorge's Avatar
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    Getting the identical enemy placements from the arcade into the MD version would be awesome. Sadly, I think that this is a big job, and this doesn't change the fact that some enemies have rather different behavior/ai than the arcade. Additionally, enemies like the harpees in the second level actually have a hit behavior where they drop to the ground, then fly back up if you hit them once. There would be a lot of work in getting the Genesis version to behave like the arcade.

    I actually don't mind the Genesis version having it's own enemy placements, even if some are kinda silly. For example, in the first level, the arcade version allows a transformation about 15 seconds earlier than the Genesis version. The Genesis version literally transforms you right in front of Neff in stage 1. It's kinda silly, you get very little time to be a monster in the genesis version compared to the arcade. I find that to be a pretty interesting oversight.

    I absolutely love this game, so I would be all about helping out however I could.

    I would Also LOOOOVE to add a mode that forces a full level play through. Like a Hardest+.

    Beast Mode
    - Game difficulty is set to Hardest
    - Neff does not transform till the final appearance, regardless of player beast state
    - Stage bonus is 175k (This is the sum of 1st/2nd/3rd stage bonus. 100k/50k/25k respectively)
    - Neff boss has about 2 and half times more life points

    I would love to have this as an option!

  9. #9
    Toejam is a wiener. Master of Shinobi SEGA-Jorge's Avatar
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    What really drives me crazy is that the Genesis version of AB is really malleable. The M2 port really messed around with it a bit. There's tons of stuff that could be done with this game that would be really fun. The Beast roulette mode was really fun. I would love the Beast Mode difficulty, and I would love a fun Castlevania beastiary sort of thing. I'd also love a stage specific score attack mode...

    It is a dream, but a simple level editor for creating challenges would be awesome. I just love fighting in this game.

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    What about Game Genie codes?

  11. #11
    Toejam is a wiener. Master of Shinobi SEGA-Jorge's Avatar
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    I imagine game genie codes should be able to change enemy hit points to a degree. The game genie is essentially just editing hex right?

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