An other job I've done after being poked by different persons.
Nebulas Ray uses a custom chip used for security (named keycus) preventing the game from booting if absent. I simply patched the program ROMs to get rid of it.
Only difference I've found so far is some stars in the background are supposed to be displayed randomly according to values coming from the keycus:
In the patched version they are aligned (no RNG):
Of course this could be circumvented by adding a subroutine generating "random" numbers using whatever fluctuating value I can find in RAM as seed for instance.
Now stars fixed!
Here are the ips files for the world version of the game: