Today is the day of releasing my longtime internal tool called Atari MapMaker. This tool was originally created for Ridiculous Reality level design. Recently I was contacted by Adam Wachowski (RR co-author), he requested couple additions to editor so he could use it for his new upcoming project… so I added some stuff inside, fixed numerous bugs and also added several nice features.
Sources are available on Sourceforge: https://sourceforge.net/p/atari-mapmaker
There is also short user guide on Sourceforge in Wiki section.