On some Android phones, you might get the following error while trying to install the game: "Failed to install on phone or external SD card".
This is most probably a problem on your phone, not with our app. Here's an external article describing the problem and solution: http://www.androidpolice.com/2011/04/19/fixing-the-couldnt-install-on-usb-storage-or-sd-card-problem-on-android/
To summarize: in a previously failed install, maybe due to lack of space, android let a file on the file system which prevents (all?) new applications to be installed.
To fix the problem, remove the file, then try again. To remove the file, you might want to use a file explorer, such as Astro. Read the above link to have more detailed explanations.
Note: another workaround is to unmount the sdcard before installing the game. We recommend you to remove the file though, as this seems to be a better long term fix,