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Here is a link to the old forum thread:


Jtool is a "jump tool" for IWBTG fangame players/creators to practice advanced techniques and design platforming. It's inspired by RMJ by Thenewgeezer. To learn more about the IWBTG fangame community, visit


(March 2018)

I've lost interest in maintaining Jtool. But I'm going to let others make their own improvements and new official versions, since Redire, Starz0r, and DuckNumbers have wanted to. So Jtool will be open source, in the sense that anyone can contribute, and I'll just approve pull requests.

To contribute, make your own fork of the repository. See the section below for releasing new versions. You can contact me at Patrick no. 0303 on Discord.

How to build

Get GameMaker:Studio from here. Recommended to use 1.4.1757 since some computers have trouble with exes compiled on newer versions.

In the script misc/mainInit, set the global variable editor_project to be the folder the project resides in. This allows GMFileSystem to work correctly when running the game from the editor's green play button (as opposed to the exported application).

How to release a new version

  1. Make sure you've tested thoroughly, preferably with another set of eyes, so that the new version doesn't cause problems with people.
  2. Update changelog.txt.
  3. Update mainInit script with the new version number.
  4. Package a release zip. (see below)
  5. Update with the new download link and version number.
  6. Update current-version.json. (Jtool reads this file from Github to check if there's a new version)
  7. Make a pull request, and message Patrick no. 0303 on Discord so I can approve it.

How to package a relase zip

  1. Compile the game as a zip (not executable or installer).
  2. Unzip that zip into a temp folder.
  3. Add the other files to the temp folder. See this image (maybe don't include source.gmz anymore)
  4. Zip the temp folder.
  5. Upload to your favorite file hosting site.


Level editing tool for IWBTG fangames.







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