ah, weird! thanks for letting me know. could you tell me if pressing X/Escape to bring up the menu works?
I can confirm that pressing escape brings up the menu with the save/close options does work. For me, the arrow key issue is that the character is always moving left. I can momentarily stop them by holding down the right arrow, but when I let go they start going left again. I can use the up/down arrows as intended. Let me know if I can provide any other info! I'm running the game on a Windows 10 machine if that helps the debug process.
Plugging in an Xbox 360 controller has fixed movement for me. I know that's not available for everybody but more data for fixes!
thanks for the info! let me message you sometime to ask you to try some things to try and pinpoint where it's coming from. it may be an issue with RM2K's native movement system, which could place it out of my hands - but i'd love to better understand why it happens.