The download area is at :
http://g4exa.lal.in2p3.fr/download
Here can be found various binary kits along the source kit.
g4exa is not available on the AppStore. Apple rejected the app because it is a demo (and... it is a demo, then it is ok), but the app is definitely constructible for the AppStore (we proceed all the steps up to the upload of the binary on iTunes Connect). Note that on the AppStore we have the g4view app which is done in the same way than g4exa.
g4exa is available on Google play (previously Android Market) for devices with at least Android-2.2. Note that the g4exa-release.apk is also available from the download area. The first version of this app had been done by using a Samsung Galaxy S first generation.
On a Mac, download and unzip the g4exa.app.zip, then click on the g4exa icon (or do : open g4exa.app, from a terminal).
At startup, the program unfolds the brem_SB part of the G4EMLOW data under the temporary directory of the app. According to the platform, the temporary directory is :
UNIX : /tmp
Windows : %TEMP%
Android : /data/data/fr.in2p3.lal.g4exa/files
iPod/iPhone/iPad : <app dir>/tmp.
With our "first generation" devices (iPad-1, SGS-1), the startup of a run is a little bit slow but after, the speed of processing of events (that includes tracking, visualization, updating of plots) appears to be sufficient to show to "people around" HEP events in a detector, even if it is pure simulation.