seems kind of impossible so far, the coin drop rate is just way too low to be able to survive more than 1 snail at a time
You really have to get a ranged unit early in order to last. Then a pumpkin as fast as possible to tank swarms. You also have to abuse the pause button for the mole to move your units when he would pop up. Its rough but beatable.
I find a pile of carrots to be very effective!
