What is Reddit's opinion of Pythagorea?

From 3.5 billion Reddit comments

I just wanna share that I learned everything I know about Euclidean geometry from an android app called Pythagorea. I think it's great.

https://play.google.com/store/apps/details?id=com.hil_hk.pythagorea

Here are 3 of them I have played, and I believe these are what you are looking for:

• Pythagorea is the one I have spent the most time in. 330+ levels, Topics ranging from lines and circles, to constructing triangles and angle bisector, 5 Stars with 3k reviews, not sure about IAP's

• Pythagorea 60 Same as Pythagorea, but based on a triangle grid, not a square grid

• Euclidea: 120 levels, 5 stars with 20k+ reviews, No ads, not sure about IAP's

Maybe Pythagorea or Euclidea?

I'd suggest playing around with Pythagorea, geometry on a grid puzzles, Android and iOS. He would probably enjoy puzzle games as well, one of my favorites is Find a Way.

I second the book and puzzle suggestions others have made. Martin Gardner has a ton of really great puzzles.