Hi, I reviewed it on the IFDB:

https://ifdb.org/viewgame?id=b2jcs44xni61lsiw&review=91829

I loved the aesthetic, especially. 

Is there any way to make custom games for this system? What exactly is it, like a game engine? Do I need a C64 to make something for it? Also, is there a way to play the original Nightmares Planet?

I finished the game. I think I'll try The Final Mask next. Hopefully your original work is even better!