I discovered this later in life too. Hit-wise it didn't do well compared to Donkey Kong or Donkey Kong Jr. Some consider it a shooter too, LOL: To compete with Galaga. This is probably why it didn't do as well as Nintendo hoped. It's kind of like what happened to Super Pac-man vs. Ms. Pac and Pac-man. As Yots said it's underrated. But still a great game.
But I love the game. Reminds me of the Nintendo Game & Watch "Greenhouse" game which I had as a kid.
DeL