Hello!
Sorry to hear you're having trouble running the game :(.
1. Sounds in the new update have changed. Go to the audio settings and try pressing the reset button.
2. On the character select, it starts on your last character selected.
3. Double check your keyboard, sometimes the controls reset when I update the input system. Player 2 needs atleast a jump to join and a roll to back out. (Also clear any duplicate inputs from player 1 so that player 2 doesn't conflict also).
Also make sure you have the latest version downloaded! The newest version fixes performance issues and a memory leak!
So uhh all the 2 player things stopped lagging right after i wrought my message. I will try fixing sounds. Thank you so much for everything you do for us and your responsiveness! Rushdown Rivals is truly underrated project! I was waiting for release and updates since the update teaser in mid 2022. I wish you good luck and good things on your way to the better game!