Tried it out, no loot ;_;
I think the core idea could be interesting and I like your monster designs but it gets too repetitive immediately, you need more for anyone to be able to judge this and provide real input. Anyhow, some ideas:
Pre-program the sequences so that it always follows a melody. You could make it so that the example you need to follow is always timed to the beat. A player could be rewarded with extra damage if it manages to push the buttons with good timing too, making it more of a rhythm game rather than a memory game.
Could mix up the memory aspects of the gameplay with other memory related puzzling, or different, more difficult "button setups". Actual "memory" the game could also be used.
Give it a good basey beat and change the tones/instrument of the button examples and inputs according to what song is playing in the background.
General tips such as adding animation to a bunch of shit, get things moving. Foreground layer with smoke or mist, Flashier attacks.