what assembler is this?

[ptorric]

i didn't have, in the golden age, an atari pc, so maybe i miss something like this.

can anyone help me to identify the software here in the animated gif?

http://sectorwars.free.fr/comingsoon.html

thank you all!

[Movax12]

Looks like MAC/65 ? http://www.youtube.com/watch?v=RkrYgFD7UFg