Quite satisfying game loop. The problems I see are:
a) With just length level 4, I was able to collect the entire square with one loop
b) The flashing of gems spawning & auto-collecting is quite painful on the eyes
c) Auto-collect removes the core gameplay mechanic (lasso). Maybe the upgrade should be really expensive, so you can only auto-collect gems 2-3 ranks below your newest one
d) It lacks any distinct game mechanic. Maybe add a multiplier for multiple gems connected in one loop, or some bombs to avoid(could get annoying)