In the next update, we plan to add the “PACIFIST CLEAR” achievement for clearing the ZAKO RUSH without a bullet or laser hit to the enemies.
We will also update the GBA version distributed as a freebie to a demo version in which all phases of Area 1 can be played, and will distribute the source code written in C for the GBA version along with it.
For more information on the GBA version, see the following article.
https://store.steampowered.com/news/app/3476490/view/547857372725379988