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Author Topic: Work in progress: Dungeon Explorer (Sega CD) Optional Patching collection  (Read 1257 times)

Greatsword

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Hey everyone! I've had this idea for a while now, and even though I do have something to show for the bit of work I've done, it still seems a bit too much of a "concept phase" sort of deal to post in the personal project section. So...

Dungeon Explorer on Sega CD. I love it, and have played through it, start to finish, ten times. Alone, once with each character, and a few more times alone as the Knight, and even once with my brother (Knight and Ninja).

It's considered a hidden gem by some YouTube personalities, and I highly recommend it. I've even seen it recommended in the RHDN forums while I was checking to see if anybody else already had announced a project on it. (They hadn't.)

One thing I noticed in various comments on YouTube and here, and it's all valid and accurate statements by the way, is that: It's hard. It's grindy. Yep. Dungeon Explorer for Sega CD is guilty on both counts.

Which brings me to the idea I've started work on. A collection of optional patches to tweak the game. I've peeked at the hex in the .bin file of my BIN/CUE rip of my copy of the game. Here's a list of what's within the patching scope of IPS format. (Note: That's not the only format I'm considering using. I'm also looking to use formats that would target ISO, for ISO/CUE. I'm shooting for format accessibility here.)

Tables for the MAX LIFE values: Self explanatory.
Tables for the EQUIPMENT values: Can be used to change purchase cost, attack, intelligence, defense, and agility boosts. All equipment has a six-byte value; each section corresponds to these listed features. Normally, weapons only affect attack, for instance, but they -can- add a point or five of defense if the hex were changed.
Tables for Level Up: A table that lists each of the "Next" point values to reach Lv. 2 through 99. Lowering it will obviously work. I don't know if anyone would ever want to raise it, but I do want to test that just to see what would happen. (The "Enemy Score" might stop at 99,999 which may or may not prevent the "Next" value from decreasing.)
Tables for item and equipment names: Not related to difficulty really, but I found these, and can change the names of whatever people want, for whatever silly reason. Like calling the "Food Potion" item "Potato Soup". However, the names consist of two six-character lines. Altering that limitation is outside the scope of my abilities.
I can change class names, but what's the point? I'll do it if somebody wants though. Haven't looked into character limits for it yet.
I can change the name of the game, to trick the emulator into thinking it's running a different game. It will generate a different BRM file (or slot in the built-in BRM, based on your settings) but that's easy enough for anybody to do really.

Any comments? Questions? Suggestions? I'd be glad to generate a few screenshots of a patched version of your choosing upon request. As it currently stands, even though I've done work on the various features listed above, the only screenshot I have handy right now is one from a changed item name patch. I'll add more soon.

Folder for screenshots: https://drive.google.com/drive/folders/1KJZl-MRhkMswE6vPAmKzXN4lphNVk5su?usp=sharing

Jorpho

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I've peeked at the hex in the .bin file of my BIN/CUE rip of my copy of the game.
Editing a BIN/CUE directly is fraught with difficulties. You'll want to copy files off the disc and examine them that way, and then re-inject them later.  (This doesn't work for all CD-based systems, but I think Sega CD is well-behaved.)

Quote
Here's a list of what's within the patching scope of IPS format. (Note: That's not the only format I'm considering using. I'm also looking to use formats that would target ISO, for ISO/CUE. I'm shooting for format accessibility here.)
I don't think IPS even works with files as large as CD images.  The Snatcher Spanish translation, http://www.romhacking.net/translations/2026/ , comes with patches in xdelta3, bps, and PPF formats.
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Tony H

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Greatsword, I was thinking of making an editor for Dungeon Explorer (Sega CD) not too long ago, but ended up just posting some hacking/code notes instead.  All of these notes use a simple search pattern to use with your favorite hex editor, and should work on any format (bin/iso/img), and any version of the game.  Maybe there's something in there that might be useful:  http://codehut.gshi.org/SegaCDhacks.txt

I agree 100%, very good game.  Hope you continue on this.
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Greatsword

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@Jorpho
Yes, you're right about hex editing being a challenge. I already discovered that there's an interesting gap separating part of the "LifeMax" table from the rest. I did try looking at the files on the disc at one point, but couldn't make heads or tails of it. I'll try again, though, and on top of that, I have an edited version to mount as well. No doubt I'll glean something from the comparison.

Also, though I have read that IPS can work on CD games, you are correct that its capabilities are very limited. Nothing that's beyond the 8 MB mark can be changed. Even though what I'm editing isn't after that point, and I'm only changing bytes that already exist, I'm going to switch to PPF anyway. I read something about patch undo capabilities, and that's probably going to be a huge pro for this type of customization collection. Besides, I may reach a point where I want to change something IPS can't touch.

Thanks for the advice, I'll put it to good use right away!

@Tony H
Thank you so much for the resources, I'll take a look!


Minor update: I've added a second screenshot. It pictures a LifeMax for the Knight that's been set to Lv. * 101, and an overpowered sword. The top tier for the Knight is normally 20. Pictured is the third weapon.
« Last Edit: April 25, 2021, 08:06:12 pm by Greatsword »

Tony H

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You probably already know this, but thought I'd mention it just to be sure.

If you make some changes to your iso/bin file, those changes will usually not work if you run your patched iso/bin file with an emulator and use a preexisting emulator save state.  Your patched iso/bin file will however work just fine if you start a new game, or use an in-game save file (a saved game made within the game, and not made by the emulator).  You can however, make a new emulator save state once you are using your patched iso/bin file, and it should work fine.

That really threw me off at first when I patched an iso/bin file and it didn't work when I used a previous emulator save state. 
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Greatsword

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@Tony H

I did indeed know that about save states, but it's such a crucial detail. Thanks for mentioning it; it's bound to save another game hacker some headaches with their project.

Also, I've taken a peek at that text file you shared. You'd found and documented a line of hex that changes the multiplier for the value of Gold from piles. That's brilliant!

It's exactly what I needed to be able to figure out how to make a less grindy hack of the game. I did a little bit of fiddling with it, and managed to get the game to give out double the gold on Freedom Hill and from chests.

My next step is reducing the "Next" values for each Level by 1/2 and combining it with the doubled Gold gain from piles of gold, then testing that out a bit.