Thanks for breaking the game! I put a patch up to hide the score issue. I specifically chose a large value score and did wonder if anyone would exceed it, but I thought I'd wait and see as I didn't go over the limit myself.
I'm actually excited that you found that strategy to 'solve' the game. As you guessed, I didn't correct the movement issue due to space - I preferred to prioritise the gameloop and I'm happy with the choice I made there. I did wonder if a strategy like you're describing would be possible - the spawn rings are there specifically to make you aware of the spawn positions to let you 'surf' the laser and not die to randomly spawning enemies - so it's nice to have that confirmed. If I did expand the game then a mechanic based around that would be interesting I think.