This app was mentioned in 2 comments, with an average of 2.50 upvotes
It's very good. It can also be quite difficult.
There's an app. too. https://play.google.com/store/apps/details?id=com.cmon.Xenoshyft
Here are links to the mobile versions.
Android:
https://play.google.com/store/apps/details?id=com.cmon.Xenoshyft&hl=en_US