[Project Log] (ROM Hack) Journey Into Plumber Subconscious

[Louis Paul]

Hello everyone, as promised I created this thread because I have a ROM hack project to develop, the game I'm modding is Super Mario Bros for the NES, the gimmick is to embed the Game Genie codes, create the lookup table to activate and deactivate the codes per level, and design the levels based on that.

One detail of this ROM hack is that I won't change the mapper, it'll stay at NROM. For that, I'm looking at the disassembly and overwriting the codes and datas that I won't use, like the demo actions and the 2 player mode, and restricting the number of worlds to 7 (7-4 would be the last level). I'm using the Asar assembly to apply the custom 6502 assembly codes.

The estimative to develop and finish this project is about 6 to 7 months, because besides gaining familiarity with the level editor, I have to test the custom 6502 assembly codes I'm putting on the ROM hack.

At the moment I don't have screenshots to show, I hope in the next days I have something to show.

Signature reserved for future use

[Louis Paul]

In the last days I was changing the title screen graphics, I used the SMB Title Editor for that, and after editing I had to convert the changes to a custom patch. For some reason the Asar assembler couldn't edit the character ROM data, so I had to use the dd command in Linux to insert the changed bytes. To facilitate the codes and graphics changes I created a Makefile to run the commands.

The next step would be to design and edit World 1-x (the first 4 levels), the plan is to introduce the Game Genie codes as from World 2-x. I will use the SMB Utility to edit the level and sprite data.

At the moment I have one screenshot of the title screen below. I also changed the player palette, HUD text, time up text, and game over text.

Signature reserved for future use

[Louis Paul]

A quick update, in the last days I created the first level and the underground bonus area, here are some screenshots:

   
   

I still have to create the other 3 levels of World Realm 1, the second level will be an athletic level, and the third and fourth levels will be underground levels.

Signature reserved for future use

[Louis Paul]

Another update, I finally created the other 3 levels of Realm 1, here are another set of screenshots:

   

Now the fun part begins, writing custom 6502 assembly code to activate the gimmicks per level starting from Realm 2, so I have to add a condition to enable a gimmick for a specific level.

Signature reserved for future use

[Louis Paul]

In the last weeks I was writing custom 6502 code to activate and deactivate the gimmicks per level. After multiple tries I finally managed to make it to work, basically the method is to read a byte from the lookup table using the level area as an index, extract the bits and check if these bits match for the gimmick to be applied.

An example of a gimmick is the torus wrap around. It's a cool gimmick for my romhack, but by default it softlocks when the plumber is dying:



That's why you don't simply add the Game Genie code to the custom 6502 code and call it a day. I fixed it by using a variable in RAM to enable the gimmick only after the level is started, and disable it when dying or clearing a level:



Now it's time to design the level with the new gimmick.

PS: just testing the WEBP animation format, if something is wrong please tell me.

Signature reserved for future use

[VinnyVideo]

I find the Endless Defeated Plumber Bug to be quite visually amusing.

Also, the WEBP embeds are working fine for me.

Course clear! You got a card.

[Louis Paul]

I find the Endless Defeated Plumber Bug to be quite visually amusing.

Also, the WEBP embeds are working fine for me.

Good news, I managed to fix the softlock while keeping the wrap around:



I use this command to convert the AVI file to animated WebP:

Code:

ffmpeg -i video.avi -pix_fmt yuv420p -loop 0 animation.webp

Signature reserved for future use