What are some alternatives?
When comparing Oak Meditation and Walden, you can also consider the following products
Headspace - Meditation made simple. Brilliant things happen in calm minds.
Sphere - The social network for meditators
Meditation Studio - Curated collections of guided meditations
Sattva - Guided meditations to inspire you to meditate every day
Metail - Metal with Swift Metal (not Metail) is a low-level API from Apple that combines OpenGL and OpenCL into a single interface.
Calm - Take a break and meditate.