As someone else mentions, the music and sound are not enabled when launching the game, but the music and sound effects adds greatly to the game. It seems that each time you spawn in you're in a unique location but I'm not sure if each level is randomly generated or it's just a big world with different spawn points. I also enjoyed the exploration aspect of this game with the destructible obstacles and finding hidden coins and chests. Getting stronger to destroy obstacles or choosing water to gain access to new areas makes the game more than just defeating waves of enemies. I made it to the end and I wonder if you can beat all of the clones that spawn or if it's impossible.
One thing is I noticed that after a game over, it takes a few seconds until the new game button can be activated. Also it's difficult to see what tiles you can destroy when starting out. At first I thought the gray bricks couldn't be destroyed but seeing a chest encased in gray bricks hinted otherwise. I do notice the particles that indicate I'm chipping away at the block, but I found that it doesn't always play especially when I'm very close to the block. Pausing the game is also odd since you click the mouse instead of something like Escape since the game doesn't use the mouse.