Since the initial release of "Eve Online", CCP has added twenty-one expansions to the game, free of additional charge to its subscribers. The twentieth expansion "Rubicon," was released on November 19, 2013, and focused on new faction ships, introduction of mobile structures, and the first steps towards "The Future of EVE" outlined by CCP Seagull. The nineteenth expansion, "Odyssey," was released on June 4, 2013, and focused on exploration and rebalancing battleships. The eighteenth expansion, "Retribution," focused on a newly re-worked Crimewatch system. It also introduced the newly rebalanced frigates, destroyers, cruisers, and battlecruisers. The seventeenth expansion, "Inferno," added enhanced graphics for missile systems, a host of new ship modules, and a controversial new "Unified Inventory" UI. The sixteenth expansion, "Crucible", was released in November 2011 and shifted the focus from cosmetic changes to game mechanics. The fifteenth expansion, "Incarna," was released in the first stage of CCP's controversial Ambulation project, also known as the "Walking in Stations" project. "Incarna" added "Captain's Quarters" to stations, the first phase of allowing players to explore stations as human avatars, as well as an update to ship turret models. The fourteenth expansion, "Incursion," was released in stages, the second of which introduced the Sansha Incursions, in which Sansha's Nation invaded constellations, disrupting all forms of activity in the area, but provided large rewards for fighting back the incursions, and an overhaul of the character creation tool, paving the way for the "Incarna" expansion.