I want interesting retro video game algorithms!

This is a bit of an unusual topic I guess, but I'm rather interested in various algorithms used by retro video games. Lately, I've been studying the password systems of old games, and I've also been looking into random number generators.

Any other interesting algorithms in video gaming?

I have one for new games.

New = Too much Ammo, limited weapons to be carried at a time. There are exceptions.

Old = Not enough Ammo, weapons can be carried all at once.

There's the old "plasma effect", especially as used with palette/colour cycling.

edited 27th Nov '14 2:40:16 PM by ArsThaumaturgis

Huh, I thought it was more of an old-game thing to give you unlimited ammo but only let you carry one weapon at a time.

I recall it was only a few years ago that someone discovered that in MegaMan 4, the attack BrightMan uses next depends on his remaining life energy, so you can keep him from freezing you by only blasting him to certain HP levels. I know from savestate abuse that most of the MegaMan Game Boy games would let you affect the randomness of the very next moment by pressing any buttons, even buttons that never do anything. I think some TASers actually decompiled the code for the first NES MegaMan to figure out how to make memory-busting glitches happen as needed—the first couple of games could be seriously broken in how they allow you to progress.

The most interesting hacks you can find, is ram level hacks. Because early generation games sometimes had to use certain variables for multiple uses.

Most famously Super Mario World

Check out the Pacman Dossier.

The original GB Tetris randomizer and the way it attempts to prevent dealing excessive duplicates of the same piece makes for an interesting read, including a bug in the code that went undiscovered for over 20 years.

Also, the way the first-gen Pokemon games stored inventory and Pokemon data is pretty interesting, but the information about it is scattered across the Internet. I recommend starting with the TAS submissions' comments on the TASVideos.org memory corruption index and Bulbapedia's glitch list.

edited 29th Nov '14 1:57:07 AM by PoochyEXE

Ah yes, I've read before how many modifiers the first Final Fantasy and Pokemon games had that were supposed to work a certain way, but really didn't work at all. I suppose it was hard to test complex games of chance very thoroughly back then.

Someone studied the code for the Toad houses in SMB3 and discovered the game only decides the item given after a chest is opened, meaning the only reason there's 3 chest in them is to give the illusion of choice.

edited 30th Nov '14 5:38:58 PM by Glowsquid

You can find mechanics guides for most major JRPGs with a quick Googling. I find Final Fantasy II's in particular to be fascinatingly bizarre

Check out this Mega Man 1 glitch run!

edited 30th Nov '14 6:41:34 PM by lalalei2001

Heh, I had seen the run that used the too-much-stuff glitch to skip to the end of the game, but not the one that only uses it to help with individual levels... and to break IceMan's green screen. Actually, my favorite part is manipulating the Fleas in the first Dr. Wily level to allow RockMan to jump past safely, when traditionally you'd want to wipe them all out at once with a Fire Storm or Thunder Beam.