thanks for playing Jibbs! i tried my best to smoothen out the difficulty curve of the waves and i guess the shooting enemies can indeed be a little hard due to the spawn algorithm.
about the game you mentioned, no i had no idea about this game i chose this pallet because i remember someone using it in ludum dare 42 and i thought it was an interesting pallet. but after watching the trailer for Sandstorm i considering to download the game so thanks for your recommendation as well