The left and right borders are now masked. I am using Player 0 and 1 both in quad-width for this.

I have the leftmost & rightmost addressable pixel at full brightness, with player 0 asking the left border.

Here I am using Player 0 to mask the rightmost border. It let me find the proper position.

Now both borders are being masked using Players 0,1.

Same as above just showing a different pattern.

Next thing to do is go hunting for my paddle controller. No digital controls in this game