In instructionless puzzles, there is usually an implied condition that gur fbyhgvba vf havdhr tvira gur bgure ehyrf. You should be able to deduce whether you need to fill in the squares or not based on this.
(this is so late/unrelated but i just realized i am your only itchio follower :Forgfrog frog and I didn't even know the feed feature existed until now)
