At the time when this application was published (April 2015) - here is no direct competitor applications in the segment of Android OS applications designed for gas reserves / resources computation.
Application source code was created to be multi-platform and in future there are plans to release version of this application for the Windows, Linux and possible MacOS. Most likely distribution conditions for these platforms would stay the same - as freeware application license. Release of iOS version also possible - but currently not planned because it would require significant financial investments.