Hello my friend, thank you for your feedback, it is really important for our game.
Have you tried the multiplayer mode? Plug your joystick and try it with a friend, maybe you will feel this difficulty level you are looking for.
Rampage Rush was a project from a 48 hour Game Jam, here in Brazil, and we will be working on it for the next few months for a future release on PC. We will take all your suggestions in consideration.
Thank you! And we hope to see you again on further updates.