Can anyone give a bit of light about the theme limitation? Maybe an example in a game term.

Thanks!

Pocket sized means anything that can fit in a pocket or smaller. Examples: in Men In Black there is a galaxy inside a marble, Alice in Wonderland eats a mushroom and gets smaller to fit through a key hole, Hank from "Ant Man" uses a tiny and portable lab to protect his research, Ant Man throws a PEZ dispenser from his pocket at pursuing badguys.

Gotcha, thanks for clearing it out with examples! Really appreciate it.