READ: This tutorial will soon be obsoleted by the release of the 20th anniversary edition of DX-Ball 2 on Steam, which will feature a board editor. However, I'm leaving it up here just for reference, or if somebody wants to try out the old method. Besides, the boardset format is getting changed in the new editon, so this still is the only way to get custom boards into Rival Ball.
my archive of old versions of DX-Ball 2 and Rival Ball
package of unofficial DX-Ball 2 tools, uploaded by Rob (note that alongside the current version of the editor and the patch we're going to use in the tutorial, it also has an old version of the editor and DXImage, the unofficial image set editor which allows you to make your own brick and background sets. I won't explain how to use them in this tutorial, but feel free to experiment with them too)
Video tutorial by McDude
Video tutorial for DXImage, also by McDude
Video tutorial by McDude on importing custom DX-Ball 2 levels into Rival Ball version 1.3
I've been talking with Rob from Longbow about the possibility of the release of the level editor for Rival Ball and DX-Ball 2. Unfortunately he doesn't have a working copy of either but did upload the old unofficial DX-Ball 2 board editor DXBoard by NOPeR alongside some other unofficial utilities and gave me permission to make a tutorial on using it:
1. If you already have DX-Ball 2 installed on your computer, you'll need to uninstall it. If yo want to keep the boards you already have, go to the directory where the game's installed (by default C:\Program Files (x86)\LDA Games\DX-Ball 2 or C:\Program Files\LDA Games\DX-Ball 2 if you have an old 32-bit computer) and copy the Boards folder to somewhere else (i.e. your desktop). You can also copy the InGameMods folder to keep any in-game music you have, since the old version of DXB2 doesn't have the in-game music installed by default.
2. Download and install DX-Ball 2 version 1.2 from the archive, preferably in the default folder (C:\Program Files (x86)\DXBall2 or C:\Program Files\DXBall2 if you have an old 32-bit computer). Newer versions don't work with custom levels, and while DXB2 version 1.0 does also work and doesn't need patching, v1.2 is newer and has quite a few new features.
3. Download the unofficial DX-Ball 2 tools package, and extract the .zip file somewhere. Copy the DXBall2.exe (might also be called just "DXBall2" without the .exe depending on how your Windows is set up) file from the "dxb2 patch" folder into the folder where you installed DXB2 1.2 (check step 2 for the default directory), overwriting the old DXBall2.exe file. This will allow you to play more than the initial four levels of an custom boardset.
4. Open the DXBoard Setup.exe file from the "new DXBoard" folder from where you extracted the files from the .zip file, and install it to the same directory as you did DX-Ball 2 1.2 (again, check step 2 for the default directory if you need it)
5. The installer will make a shortcut to the editor in your Start\Programs folder, so open it. Click on LOAD if you want to open an already-existing roundset, or NEW to make a set yourself. First you'll need to choose the brick set you'll use, so pick one from the list (brick sets are the .img files with Brick in their names). Next, go to Board>Set Board Background... then click OK and then Choose Background File. In the window, choose the set you want. Background sets are .img files with Background or BG in their names. That's it, you're ready to make your set! Make sure to save it in the Boards subdirectory of the folder where DXB2 is installed to be able to play it, though that folder is open in DXBoard by default.
6. To add new levels to the game, whether downloaded from the Internet or perhaps from your copy of the Boards folder, copy all .bds and .bdz and .img files to your Boards subdirectory, overwriting any other files. Do the same thing with your InGameMods folder if you copied it in step 1, only this time copying all files. If you can't see the extensions such as .bdz or .exe, go to File Explorer, press F10, go to Tools>Folder Options>View tab, uncheck Hide extension for known file types and click OK.
That's it! If you're having problems or are getting error messages, then you probably haven't followed the steps correctly. Uninstall DXBoard and go back try again from Step 1. ;)