Just a Line, still labelled as an AR experiment. Simple in idea and execution, it has the potential to become an addictive example of AR on your smartphone. Provided it becomes even more widely available.
This drawing app is definitely not going to win any awards in the paint app category, you only have one colour and one line width (for now). So it is basically the digital equivalent of a white chalk you can draw with on almost anything. Although, this one is a little better because it does not leave a mess and even lets you draw in mid-air.
The concept behind Just a Line is simple, you simply draw with your finger. The magic happens when you move your phone away. The marks made will stay as if magically suspended in the air. And they stay that way no matter which way you move.
No one will be able to see your magical creations except through your phone and only as long as you're running the app. The app does allow you to record a short video clip demonstrating your mad AR art skills.
The only problem is that the number of devices that supports ARCore is extremely low, and even then it might be a hit or miss (reported to crash on certain Galaxy Note 8 models). If you are looking for a slightly better AR painting app, you can also try PaintAR, which has similar concepts but more colours to play with, but it also requires ARCore.