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View topic - SMS Ninja Gaiden Hack - Avoiding the infinite magic points

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  • Joined: 18 Apr 2021
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SMS Ninja Gaiden Hack - Avoiding the infinite magic points
Post Posted: Sun Apr 18, 2021 8:53 pm
Hey all, this is my first ROM hack.

On Ninja Gaiden for the SMS, the original ROM, once you reach 999 magic/weapon points, you can use the secondary attack infinitely without spending magic points. This can be done still early in the game, and simply makes the game too easy, specially because there is one of this attacks that makes you invincible and still causes damage to enemies.

I found out that the memory address 0xDFBB, which is normally 0, will be set to 0xFF when 999 is reached. This is used to avoid incrementing it more, but also at 0x50DF it is used to skip the routine that decrements the magic points when the secondary attack is used.
I patched this check to instead set 0xDFBB to 0 again and continue to the code that decrements the points.

One curious side effect, the points are normally a multiple of 5 until it reaches 999, after that, when it decreases, the less significant digit of the points will always be 9 or 4, but I tested depleting the points and collecting 999 again without any side effects.

The patch is attached.

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  • Joined: 14 Jul 2008
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Post Posted: Tue Apr 20, 2021 12:00 pm
That's great. I suppose this can be used with the prototype version too? I prefer that to the final release because of the much more fleshed out cutscene script.
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  • Joined: 18 Apr 2021
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Post Posted: Tue Apr 20, 2021 7:49 pm
Wesker wrote
That's great. I suppose this can be used with the prototype version too? I prefer that to the final release because of the much more fleshed out cutscene script.


Hello, I am not aware of this prototype, do you know where I can find it?
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  • Joined: 08 Jul 2001
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Post Posted: Wed Apr 21, 2021 12:00 pm
When we originally released the first dump (september 1999) we also had a prototype with it (at the time we didn't know it was a prototype):
https://www.smspower.org/db/ngaiden.htm

Emu-france normally has our download mirrors but weirdly can't find that ngaiden.zip from it:
http://smspower.emu-france.info/

CRC 1b1d8cc2 is final rom
CRC 761e9396 is the prototype rom
Should be widely available.
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  • Joined: 01 Feb 2014
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Post Posted: Fri Apr 23, 2021 6:22 am
dellagustin wrote
This is used to avoid incrementing it more, but also at 0x50DF it is used to skip the routine that decrements the magic points when the secondary attack is used.


Wait, does that mean it's actually intentional? The latter seems to suggest that.
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Post Posted: Sat Apr 24, 2021 3:42 pm
Kagesan wrote
dellagustin wrote
This is used to avoid incrementing it more, but also at 0x50DF it is used to skip the routine that decrements the magic points when the secondary attack is used.


Wait, does that mean it's actually intentional? The latter seems to suggest that.


It seems so, but maybe it was a testing left over... who knows...

Wesker wrote
That's great. I suppose this can be used with the prototype version too?


I created a new patch for the prototype.

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