this game has a lot of that arcade "tough but fair" energy that's a joy to play.
the implementation of the enemies is especially good, because they feel consistent, but they're also fun to play against because they cause unpredictable destruction to the playfield. if you update the game, it would be really cool to see what different new kinds of enemies could be made with perhaps different ways of destruction.
if i were to critique any existing stuff, the player movement could be refined to have more control (perhaps variable jumping), and the utilization of the destructible grid against the enemies as you fight is totally possible but could be a little more involved... i wish there was other attacks like a throwable bomb or even the ability to dig under the enemies a little easier, stuff like that to encourage messing with the destructible ground would go a long way in boosting the amount of fun one could have with the game (which there already was plenty to be found).
either way, this game is great as is and has plenty of room for cool new ideas, well done!