So I've started converting the ROM vectors from the Asteroid game into 68000 assembler. I've also been experimenting with the different GPU effects available in the Gameduino. I've used additive blending and some blur, reduced alpha to get a sort of glow effect depending on the brightness values in the original roms.

Each point is in the format Brightness, dX, dY

* 7 points for a ship
ship:
        dc.b 0,4,6,7,-8,0,7,-4,4,7,8,-24,7,8,24,7,-4,-4,0,-20,-6

* 2 points for thrust
thrust:
        dc.b 12,8,-4,12,-8,-4

* 13 points per rock
rocks:
    rock1: 
        dc.b 0,0,-4,7,-4,-4,7,-4,4,7,2,4,7,-2,4,8,6,4,8,6,0,7,4,-4,7,0,-8,7,-4,-4,7,-4,4,0,0,0,0,0,0
    rock2: 
        dc.b 0,-4,-2,7,-4,-2,7,4,-4,7,4,2,7,4,-2,7,4,4,7,-2,4,7,2,4,7,-4,4,7,-2,-2,8,-6,2,8,-4,-6,7,4,-4
    rock3: 
        dc.b 0,4,0,7,4,2,7,-4,6,7,-4,-6,7,0,6,7,-4,0,7,-4,-6,7,0,-4,7,4,-6,7,6,0,7,6,6,7,-4,2,0,0,0
    rock4: 
        dc.b 0,-2,0,7,-6,-2,6,0,-2,7,6,-4,7,6,0,6,-2,4,7,6,0,7,0,6,7,-4,6,7,-6,-2,6,-2,2,6,-4,-4,7,6,-4

* 12 points
ufo:
        dc.b 0,4,-2,12,-8,0,0,-6,4,13,20,0,13,-6,4,12,-8,0,13,-6,-4,13,6,-4,12,2,-4,12,4,0,12,2,4,13,6,4

I obtained the original values from https://www.computerarcheology.com/Arcade/Asteroids/VectorROM.html although it seems that some of the divisors are incorrect, but fairly easy to correct. As you can see the original shapes are now appearing on screen. 4 types of rock, the player craft and the UFO.