"Forest team partners with a real-tree-planting organization, Trees for the Future, to plant real trees on Earth. When our users spend virtual coins they earn in Forest on planting real trees, Forest team donates to our partner and creates planting orders."
Forest is an app that helps you stay focused on the important things in life. It's a simple concept - start a productive focus session, plant a tree, your tree will grow while you focus on your work, if you leave the app, your tree withers. If you really like collecting awards and achievements this could work for you! Bonus: Use the coins earned from your productivity sessions to plant up to 5 real trees with Tree for the Future.
Also, from the creators of Forest, they have Flora. It's like focus with friends - take it up a notch by focusing with a group. If anyone leaves the app, the tree dies. Flora also has a real money incentive - pledge money to stay focused, if you fail, you pay the actual money to charity to plant a real tree.