Xen's atmosphere seems to be similar to that of Earth's, as the Xen wildlife appears to have no trouble surviving on the planet. While it is possible that the 'islands' are small chunks orbiting a larger and unseen planetoid, these unusual physics strongly suggest that Xen occupies an alternate dimension where conventional physics may simply not fully apply. Another feature is that gravity is always directed downwards, rather than towards the asteroid, so that one can actually fall off an asteroid into the void below. However, given that Xen is comprised of low mass asteroids, it is surprising that there is any appreciable gravitational pull at all, let alone a pull strong enough to retain an atmosphere. Xen is notable for having greatly reduced gravity compared to Earth's. An example of the highly organic asteroid cavern-like areas explored on Xen.
