Both players are being used to draw all the sprites, the 3 dotted lines are drawn using the missiles and ball.
You can move the blue sprite around with the joystick, as it crosses paths with the other sprites the players will flicker. Hold fire to move slower. The white dot in the radar will show the location of the blue sprite within the world.
Right Difficulty = A to show the use of HMxx to shift the missiles and ball back & forth on every scanline.
The missile/ball routines will probably take a bit to migrate over as I'll have to rewrite them to take advantage of the new support for HMxx.
For Harmony on a 2600*
* we discovered an issue with Fast Jump that required an update to the Harmony/Melody driver as well as Stella's implementation of it. As such, you'll need Stella 5.0.0-pre8 or newer, which isn't available yet.
Addendum: Per request, added screenshots using the Fixed Debug Colors. Do note that the colors have changed to make it easier to know which color's which (ROYGBIV), plus the debug colors are now displayed on the TIA Tab!