There are five arenas right now in Stellar Sphere. Two more coming for free after release. Remember that all the arenas can have the gravity deactivated by default, but you can activate it whenever you want in different intensities.
First Arena: Stellar Short.
Stellar Short is the basic arena of the game. It’s in space, and it’s where the tutorial develops. If you want a fast game, choose Stellar Short.
Second Arena: Stellar Large.
Stellar Large is an extended version of the previous one. You’ll find that reaching the wormholes to score is harder. If you want a slower game, choose Stellar Large.
Third Arena: Stellar Egypt.
This is an arena placed in a planet where an advanced civilization has developed a new egyptian civilization as they did in Earth.
Fourth Arena: Stellar Chaos.
This is exactly what it says: chaos. This arena is in a chaos environment, where random accidents might occur anytime anywhere.
Fifth Arena: Greece.
Atlantis was not destroyed; was abandoned. Now the relics of those times and the atlantis are the watchers of the Stellar Sphere games in this distant world.