A really great time killer, but please change money icon to emerald, because emerald is Money in minecraft world and there is no dollars in this game lol, im also having an idea, but its hard to make - why dont we add blocks to this game as barricades? like, you place a wall and monsters hardly getting through it, but the problem is that there is a really little space for barricading. and, obviously, add more monsters and even bosses on every fifth level, because fastly killing slimes is boring, and you can understand it. But its a really GOOD, i dont know what else to say, its really great game.
EDIT: i actually wanted to see skeletons, their arrows must be slow because with fast arrows, they will become more harder than first boss (or not if there is going to be shield added). i actually even wanted to see enderman which with some chance can dodge and even teleport behind the player. I even wanted to see Magma Slimes which would give a player ignited effect for 3 seconds. And lastly, i want some sort of skill tree, like HP leveling up, 10% more gold and etc. these are all my ideas for the game for now, im going to think 'bout more ideas for the game.