I've experimented with more accessible rhythm indications, like flashing screen or something like the Crypt of the NecroDancer uses, but decided to leave a barely noticeable UI element as it is only supposed to be used as a quick reference at the beginning.
Sorry you had to look at it to catch the timings! That was definitely overlooked.
The music and enemy movements are synchronized to the same rhythm the player should use, not sure if additional sound would help, but it is worth a try (can't test it on myself though, need to find someone who wouldn't mind suffering through a rhythm game without prior experience ¦3).
Yes, there is a list of things I wasn't able to finish in time, and I would like to address it post-jam.
One of the items there that might be helpful is an input delay calibration, as different devices may give you different responses to correctly timed actions (especially when playing with wireless headphones that add a huge audio delay, making it almost impossible to find the right time).
