FAQ
Q. Which files can I open?
The following files. Drag and drop a file onto the window, or choose File → Open… from the menu.
| Extension | Contents |
|---|---|
.nes |
iNES format ROMs (containing CHR-ROM) |
.bin |
Headerless CHR data |
.zip |
The first .nes file inside the ZIP |
ROMs that use CHR-RAM (and contain no CHR-ROM) cannot be edited.
Q. On macOS, I get a message that the app can’t be opened because the developer cannot be verified
The macOS build distributed on GitHub is not notarized by Apple, so macOS shows a warning the first time you open it. You can open it as follows:
- Try to open R-CHR once, and close the message
- Open System Settings → Privacy & Security
- Click Open Anyway next to the message saying “R-CHR” was blocked
From then on, it opens normally.
Q. Can I use it on an Intel-based Mac?
The macOS build distributed on GitHub is for Macs with Apple silicon.
On an Intel-based Mac, please build it from the source code with cargo run --release.
Q. The colors changed when I imported a PNG
Colors in the PNG are replaced with one of the 4 colors in the current palette set. Switch the mapping strategy in the import dialog to check the result in the preview.
- Palette Match: best for indexed-color PNGs drawn with the NES palette (for example, in Aseprite)
- Index Direct: for PNGs whose first 4 palette colors are set up to match CHR colors 0–3
- RGB Approximate: for full-color PNGs, screenshots and so on. Setting the palette set close to the colors of the original image improves the result
You can undo an import with ⌘Z / Ctrl+Z.
Q. I can’t import a PNG
Open a .nes / .bin file, or create CHR data with File → New File, before importing.
The image is pasted starting at the tile selected in Bank View.
Q. How do I change the display language?
Use the English item in the menu to switch between Japanese and English.
Q. Where can I find detailed usage instructions?
See the README for details on each tool and keyboard shortcut.
System requirements
| OS | Supported |
|---|---|
| macOS | macOS 11 Big Sur or later (the distributed build is for Apple silicon) |
| Windows | 64-bit (x86_64) |
| Linux | 64-bit (x86_64) |
Your data
R-CHR does not connect to the internet. The contents of the files you open are processed only on your computer and are never sent anywhere. For details, see the Privacy Policy.
Bug reports and contact
Bug reports and feature requests are welcome on GitHub Issues. If you don’t use GitHub, please email us at:
When reporting a bug, the following information helps us investigate:
- Your OS and version (e.g. macOS 26.0 / Windows 11)
- R-CHR version
- The steps that led to the problem and any message shown
We can answer in English or Japanese.