I have weird campaign ideas and no idea what systems to use.

The title really does sum it up but I’ll get a bit more specific.

I had an idea for a campaign where they had to play as cats in a zombie apocalypse. I have no idea where to even start with that.

I had an idea where they would play as a group of men in the Lisa the painful universe looking for a lost treasure.

Finally I had an idea of a 40K campaign where they would play as a group of nightlords struggling to get by akin to the nightlords trilogy. I saw black crusade but I don’t know where to get a copy.

Let me know if yall had any suggestions!