Theme Name (something short and catchy): LEGO Rome
Characters (who is good and bad guys?): Romans and Gladiators are the Good Guys, the Monsters of Greek/Roman Myths are the bad guys.
Conflict (why do they fight, and what do they fight over?): They can fight in the arena, over treasure, in a labyrinth, etc.
Setting (where does the story take place?): Ancient Rome (with a more magical/mythical setting).
Background Info (if relevant): Gritty sets with warriors and lots of minifigures, treasure, fictional and actual locations.