This is a neat idea and a mash of genres that works well. If this had some more content and a few QoL changes i'd buy the full version.
Minor gripes:
-The high score text is covering the 'easy mode' button. Easy fix but took a min to figure out
-Dunno if it was my setup but the music didn't quite line up with the prompts so i was just timing visually.
-Feedback system for correct rhythm would add some juice
-Another commented the zombies could move in rhythm, that would be consistent with the theme and work well.
Overall awesome job had fun thnks