You nailed the theme! You made good use of your title too. I thought to myself, "Why are there no gladiator pits in this module?" about half a second before I hit the section where you battle the three-armed troll in the gladiator pit. Four colour-coded martian clades, scientist princesses, pit fighting, earth tombs with Mars portals, the garden at the end: you didn't let anything go to waste.
I liked the way you've presented several different locations here too. Tomb, Surface, Castle, Pits, and Garden go a lot harder as a group than the mountain fortress would have alone.