I always found discoverability of vim commands really poor and this game really helped me. In practice mode you can see an optimal solution to the problems which helped me to internalize new ways of achieving the same thing in less keystrokes. Would recommend if you feel inefficient in vim.
TIL there are two units of measurement that are both called ton but confusingly are not the same as a ton. One is a tiny bit more than a ton (1.016 tons) and one is a bit less (0.907 tons). Apparently people use the prefixes long and short to differentiate them, at least that part is intuitive.