Hi there! Thanks for playing, and reporting this issue.
I made the control setup in haste, and look back it may not have been the best choice. I'm using a QWERTY keyboard, but it's possible my layout doesn't work on some other keyboard layouts.
The "<" and ">" keys are also the "," and "." keys on my keyboard layout, and those are the actual attack keys for P2. (Comma and Period keys) They looked a little silly on my "help" screen so I instead listed "<" and ">". Try the comma and period keys and let me know if those work!
Honestly, I'll probably go back and change the P2 keys to something like "O" & "P"... I was trying to find a layout where 2 players could comfortably play on the same keyboard XD