I thought it was possible given the simplicity of the idea. But it took a few days to do it: I now have a steady 262 scanlines (on Stella).
I am going to quit programming for a few days because the heat wave is expected to begin tomorrow. And when it's hot, I call my room "the oven" because it's hot. I don't like being really angry and hot at the same time because it literally hurts. And I'm at a good stopping point now.
I don't know what else I can do with the game. I have ~170 bytes left. But I think the game is pretty much complete. I put in all my ideas. I even got the bee to move in a straight line. I put in a hornet that chases you around for a little bit. And the flies are there to swat. And it's 2k. So now what? I don't know.
After the heat wave, I will test my game on a real 2600. It's really too hot to do it now. How hot is it? A few days of 90+ temperatures they're predicting. But it's May. We have an excessive heat watch. And I'm tired. My wrists hurt because I was typing in code for long periods of time.