This looks like a duplicate install issue. This probably means you have more than one version of dungeon quest installed on your device and it will not let you install the new version. You need to uninstall all copies of dungeon quest and then update from google play.
@Frayed I wish we could do localized pricing, but its more of a fault the older tech we used to build DQ than anything else. We will make sure we address this issue in the future!!