Raiders of the Lost Ark

[dr. kwack]

Hello everyone. It's been a long time since I've attempted a hack and I wanted to get some ideas from any interested parties...

 

I want to do a hack of Raiders of the Lost Ark. It's one not many people have tinkered with. I'm looking at a graphical hack for the most part. I want to "shape up" Indy, the Thief (make him look a little more like Toht- who I always assumed he was supposed to be), jazz up some of the items in the marketplace and so on.

 

I got to thinking, however, that with all of the great hacks people have done over the years to Adventure, is it possible to jazz up some of Radier's rooms? Maybe give the opening room a bit more of a rock like look, jazz up the walls in the marketplace, that kind of thing,

 

If one with more talent than I would really get into this- would it be possible to throw in a few action scenes? Indy gets a gun but doesn't use it much! Nazis? Cairo swordsman? How about making that whip more of a line than a dot? Just ideas.

 

I will start tinkering this weekend with the usual sprite stuff, but if anyone has any ideas or wants to join in feel free!

[raindog]

You might be able to edit both the sprite and level data using something like Hack-o-Matic, depending on how HSW and company stored it originally. That was how I got my start, then started playing with disassemblers to figure out where the colors and stuff were stored so I could hack those too.

 

If by "jazz up" you mean things like adding gradients to simulate shadow and things like that, you'll be messing with the kernel, but you don't really need a VCS 101 class to learn that every line of graphics is displayed in real time by your code, every opcode (command for the CPU to run) costs a number of cycles and you have 76 cycles to play with per line (or you won't even get a usable image on screen). You'll need to learn how to reassemble code after tweaking it, which is (usually) a lot easier than writing it from scratch.

 

More substantive changes like adding rooms, showing the whip or adding enemies who shoot back will require more substantive code and possibly a bigger ROM size. I never played Raiders back in the day (not being a fan of the movies) but it's an impressive game with a lot going on for an 8K ROM, one of the few Atari games that benefits from using an Xbox controller (mapping both sticks and multiple buttons) when playing in Stella.

 

If you achieve the things you mentioned, you'll automatically become one of the better homebrew coders out there.

[dr. kwack]

Thanks for the info!

 

Yeah I know some of these ideas are pure Fantasyland, but I was just curious if anyone had ever considered such things.

[dr. kwack]

Well, this is turning out to be a little tougher than I thought. Just finding some of the sprites has been a pain!

 

So far- I changed the thief to Toht. He's a little more human looking and sorta based of Clark Kent from Atari's Superman cart.

 

In the inventory bar, I have changed- The Whip, Headpiece, Parachute, Ankh (rough stage- it is now a crude looking grappling hook- that's gonna change soon), and the time piece.

 

On the main screen the treasure room now contains a box (this may change), I've fiddled with a few frames of the spider, the bullets in the Black Market are now one bullet icon, and I think that's it.

 

Can't for the life of me find the boulder or whip (from the opening screen), the Raving Lunatic, the Arabs, the Ark, or the Sundial version of the Timepiece.

 

I've opted to leave Indy as is. He's kinda iconic in this version.

 

Feel free to tinker, critique, ignore, etc.

 

raiders6.bin

[raindog]

Thanks for the info!

 

Yeah I know some of these ideas are pure Fantasyland, but I was just curious if anyone had ever considered such things.

 

I don't think any of the things you suggested are "fantasyland" at all. They just require the same person to have enough interest in Raiders to make the changes, the knowledge of VCS coding to make it happen, and the free time necessary to execute.

 

It may seem like a long shot, but that's what making a decent Pac-Man seemed like to me when I started my own hack project 14 years ago, for example, and what other people have done with it in the years since I burned out go far beyond what I thought possible.

 

What you've done so far looks good, what I've been able to see of it -- I still have no idea how to get past the second screen without dying, and the game seems to mix "up is north, down is south, you're viewing it isometrically" and "up is up, down is down, you're viewing it as a cutaway" willy-nilly. I don't think you'll find the boulder and whip easily because just the way they drew the whip makes me think it's a missile being drawn by staggering its horizontal position, and the boulder looks like something similar is going on, maybe drawing it mostly with playfield and using the missile(s) to make the edges jagged.

[Nukey Shay]

Stella's debugger is good for this sort of thing. You cam click anywhere in the screenshot and use option "fill to scanline" to read and step through the code which is drawing the portion you are interested in. The rock and whip, for example, are drawn using GRP0. The code shows that the data is coming from ram location $DD & $DE (indirectly, so add the Y register to that). This points right at $FFD9-$FFDE. The kernel routine for this specific area automatically shifts every other line by 1 pixel without altering the current bitmap value (each data byte is drawn twice, but shifted to the left or right).

 

You'll find that the other "missing" screen images are drawn similarly...IIRC each one of them using their own dedicated kernel routine.