Stu's Incredible Pac-Man Hack Challenge

[highrise]

had already done that actually, as well as modded the graphics and did some stuff with the font.


Those side entrances shouldn't be a problem, and there's quite a lot of free memory available as far as i can tell.

[highrise]

ok, so I got a font in there. The entire game runs using the ROM char print, everything is basically done using what are essentially UDGs.




An arcade font does make a big difference. But let's face it, all we are really doing here is polishing a you know what.

[highrise]

the number of dots you have to eat to complete the level is held at address 28365.

[highrise]

All fun and I'm more than happy to do this hack but I'd hardly call it 'arcade', I mean, it plays in a very jerky way with 8 x 8 pixel characters and it definitely doesn't have the number of dots, or more particularly the AI of the original. I'm not saying it's unplayable but it's a million miles away from being anything like the arcade! I wouldn't want the work I've done (with the help of Mat) here to be considered anything more than a hack job to be honest.

Meanwhile, the editor now counts the dots for you which is handy.

[highrise]

and more specifically, since I AM working on a mini version of Pacman which will be a lot more like the arcade than this, I definitely wouldn't want this to be confused with that.

[highrise]

yes, well I thought the same when they called it 'Donkey Kong Arcade' when basically it was just a hack and wasn't really any more like the arcade than the original I think a hack is a hack.

[highrise]

Pac-Hack is kind of cute though. If I finish it I will more likely release it as something people can edit. I just like things described as what they are. If someone puts the time in and makes a really nice new version of Pacman that played like the arcade they could call it that couldn't they. If I downloaded something called 'Donkey Kong arcade' and found it was just a palette swap I'd be a bit disappointed.

[highrise]

The default start X Y addresses for the ghosts are as follows:

RED 26564,26565
GREEN 26572,26573
MAGENTA 26580,26581
YELLOW 26588,26589

I now have the ghosts starting in their arcade default positions. However, doing this highlights an issue because when the red ghost turns blue and you eat it, it returns to its starting position, but does not go back to being red. Instead it stays blue. This allows you to eat that ghost several times over, getting a lot of points. So that is something that would need fixing, either by making the 'den' one space wider, or somehow causing the red one to reset back to red when it reaches its home space.

EIther way, the ghosts start in the right places.

Apart from that, it should just be a case of fixing the tunnels exits and making the power pills flash.


I've been calling this pac-hack throughout the thread and I think I'm pretty happy with that.

[highrise]

good shout. Or maybe better yet the Red one could start at the barrier where Pacman can't go.

[highrise]

ok, so if I put the red one over the barrier it creates a gap that means you can enter the maze, so that won't work. Putting the red one in the lair works however. It's not arcade authentic but it might do for now.

[highrise]

scratch that. If I put Red inside the barrier, he can't get out. So that's scuppered that idea. Going to have to do something with the reset which means more digging.

[highrise]

difficult to say. I'll continue to experiment.

[highrise]

I guess this one will do

[MatGubbins]

That's a lot of code searching to get those bits fixed. Good job.

[highrise]

thanks. I have one side of the tunnel working, just need to figure out the other.

[highrise]

both tunnels now working for Pacman and the ghosts. Now to get those power pills flashing.

[highrise]

the addresses for the power pills, which are flashed using only attributes are held here:

$5EB7
$5EC0
$5EC9
$5ED1

[highrise]

ok, the dots are sorted. The game is more or less complete and playable now, bar a bit of polish. I'm going to send it to my Patreons now to get some feedback and then put it out shortly after that.

Thanks for the suggestion Stu, it was a fun challenge. Don't worry about the money, but feel free to buy some of my games or support me on Patreon yourself www.patreon.com/happycodingzx

[highrise]

by the way Mat, how did you go about finding where the map was located?

[highrise]

Thanks, no problem. I kind of dropped the Rally X mode of Terrapins when someone made a pretty nice version of Rally-X. I guess I might come back to it at some point.

[MatGubbins]

Map finding can be a hit or miss situation. I use EmuZWin 2.7 emulator (on Windows XP) and scroll through the memory map.
Tools > Sprite Finder
This will bring up the entire 64k of Spectrum memory (ROM, Screen Ram and above). By using the width setting it allows you to put bytes side by side (upto 32 bytes) and if you're lucky there might be something that looks like map data.
If you can't find a map in a certain game then it will be compressed, stored as a bitmap, or just a random jumble of data.

The memory address is located at the bottom left and will update when the mouse is moved over the data - it doesn't show the byte value though.

The you can either use the Debug Window to change values, select Dec or Hex values with '10' on the menu bar, and test the map, the assembler allows you to extract the map data as a text file (use the disassembler) with all the DEFB bits put in.

As with every emulator, they take time to learn how to get data in/out of a game.

[highrise]

I see. I used a similar principle, but small routine that I put at the top of memory. It fills the screen with vertical lines, then goes through memory dumping 768 bytes to the attribute memory each time you press a key. In this way you can see data emerging. This is how the map data comes out on screen when properly aligned.

[highrise]

here is part one of the 'Let's Hack' video.

https://youtu.be/o9XS6JxfUBo

[highrise]

This has now been fixed. As a special bonus for those who support me on Patreon, I also added some panel artwork to make it look like a tabletop.

[MatGubbins]

f you move the hi-score one char to the right then it'll look cleaner. Yeah, it's a bit more code hunting, but you're enjoying it.