Great job on the submission - I really enjoy having games that have a single button like you do here, because it means that you don't have to mentally remember a bunch of different hot keys / controls. So many games can be challenging just because you have to remember everything you need to press to get the information or state of the game.
I do think the instructions were a bit abstract, and I definitely triggered a 2 player setup on my first run unintentionally. The absence of extra buttons definitely has their drawbacks, and I've hit a bunch of them first-hand as well, so I can understand the design challenge here. I'm not sure what the best way to solve it would be, but potentially an announcement when changing player 1 or player 2's set up would be good? 🤔
I think, it was slightly hard to get a sense of the total track length and could have been cool to have some starting affordance there (a set number of ticks you hear before starting). I think some score goals for single player would be also super neat!
Again, great job on the submission! I hope other games strive for this sort of simple and flexible interface in future jams!