Nice but I had hard time to finish due to 5 seconds or more response time every 10 moves for the second half.... otherwise I liked it : interesting mechanics, not too hard.
Well surprising because 21 is quite "logical" in my opinion (and easier than 20...) - this is the beauty of this game : each player has its own way of playing it. Hint : gur serr fdhner yrsg gb gur "9" vf * irel * hfrshy