Outer Planets Expansion Pack Suggestion Box Spacedock Pack (OPX and associated mods) About Long ago, one of my first planet mods I ever played with was the famous Outer Planets Mod. For a while, I had great fun exploring the various moons, but soon I realized that something was lacking. The moon systems of all the gas giants felt almost... empty. Thus, I set to work to rectify this problem. Now, years later, I actually know how to planet mod, and I am proud to announce