Yeah, so there's actually an R package from RStudio, learnr, that does just that: progressive reveal, code checking, etc. (See the Exercises section for more detail).
In my limited experience of coding interactive tutorials, it can be surprisingly tricky to set these types of things up across various platforms (I have no clue what the Hacker Rank setup is). But, given learnr is designed for R, that should make for an easy/easier, good match.
As per usual, time is the limiting factor, but based on the activity in threads such as the one below, it's the type of thing that could do well under open development.
cc @jessemaegan curious if you think this would have made a difference in early stages of the open R4DS course!
