i have done 3 self imposed challenges of this game, and at least partially succeeded in all of them, here is it.
the ranks:
gold, get all the tomatoes (certain exceptions apply)
silver, just finish the game.
rust, fail
no up challenge:do not press the up button, only left and right: gold
no left challenge:only go up or to the right:silver
no tomatoes challenge:collect a total of 0 tomatoes, gold? (all=none maybe?)