Mobile multi-purpose devices such as smartphones are progressively replacing digital cameras; people use their smartphones as everyday companions and increasingly take pictures in their daily life. Tagging is a way to organize huge collections of photos but raises two challenges. First, tagging (especially on mobile devices) is a boring task. Second, remembering the assigned tags is important to find images with tags. We propose gamification for more entertaining tagging. Most gamification approaches use crowd-based assessments of good or bad tags, which is a good way to prevent cheating and to not assign improper tags. However, it is not appropriate for personal images because users don’t want to share every image with the crowd. We developed and evaluated two mobile apps with gamification elements to tag images, a single-player and a multiplayer app. While both variants were more entertaining than a simple tagging app, the single-player app helps users to remember significant more tags.