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Brick Drop is a game in which you play as a square moving side to side that has to dodge bricks. To stop moving simply tap and hold as long as you would like to remain still. Brick Drop is available on the google play store.
Elemental is a simple open-source life counter for Magic the Gathering. It's available on the google play store, and has a web version for ios users.
FreeXT is the ultra-minimalist, open-source note-taking app. It's available on the App Store, and Google Play Store.