> assumed you just found the 'ghost' of two-player mode left
> over by Secret of Mana and enabled it. Did you actually
> manually hack in all of the controls? If so, I am very
> impressed.
There was no existing 2 player code that I could find. Despite that, replacing the controller input ASM to read from both controllers was relatively easy. A bit of RAM had to be used to store the extra input and keep track of which player had which character, as the game only cared about which character had the camera focus. Diverting the input to the two characters for moving/fighting and turning off the AI also wasn't too difficult, as the original game already lets you take control of the dog so it pretty much had to have existing code for at least interpreting controller input for either character (although I did have to modify them, to use the correct input for each). Getting the rest of the game to cope with 2 human players though... -_-
Probably the biggest issue was fixing the multiple character freezing bugs while testing the patch. It was caused by the game freezing a player's character to talk to someone, then unfreezing the wrong character when the text window went away due to the game using some odd method or function instead of the regular one that I had modified. This was on top of getting the game to even recognize and display the correct text depending on whether the dog or boy was trying to do the talking (every time I thought I had it fixed, I'd discover some other random person a few days later that used a completely separate bit of code), not to mention the action buffer overflow issue (while one player talks to someone, the second player tries to talk to someone else or leave the area x times, causing the game to crash). And of course, having to track down and modify just about every single place in the game it tried to interpret the controller input (while that wasn't unexpected, practically every single menu screen had its own separate routine that had to be diverted).
Although there were some problems I somehow caused myself that I had to fix, like a certain pyramid issue (dog enters pyramid, turns into boy and becomes trapped, plus character outside is frozen... after tracing the strange code that's supposed to handle character switching in that area, I just ended up commenting out most of my own select button code and working around how the game handles it).
But I did find something of interest when I examined VRAM. At the time I was trying to find a place to fit in a couple extra tiles for indicating which player had which character. To my surprise, I discovered a few numbered tiles (1-3) drawn on the ends of charge gauges already in there. At first glance I thought they might have been left over from early plans for multiplayer support. But given that there were also flipped tiles intended for the other side of the charge gauge, I realized it's just as likely they were meant as an alternate method of displaying the weapon charge. But either way, it was nice of the designers to leave the tiles in, as they came in handy.
Er, sorry to ramble... ^^ But while it was a fairly short project, it was still rather interesting trying to get 2 player capabilities into SoE.
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