I would imagine they would make a death star like planet, basically something with no outside atmosphere. Maybe with a horror setting like in Alien or Dead Space. Corridors with intense spawns of mobs connecting a few biodomes, which would be a bit friendlier for humans. Think steel - I bet that would be their thing
lots of cut scene video. Really nasty boss mobs (that will loot 25 nova fragments) no wait. Maybe that is the Capcom planet
A Yu-Gi-Oh! planet. Mobs drop cards and you can duel against others in PVP zones with the cards you loot.