TinyTap. TinyTap is a free iPad app and free Android app that lets you create and publish educational games. One of the features of the app is the ability to create "Houdini" mode games. These are games in which students answer questions to reveal an image. Watch the following video to see how TinyTap's Houdini mode works.
TinyTap's original game template enabled teachers to create identification games. That is still a feature available in the app along with many other features that you can learn about in the following playlist of tutorial videos.