Planet Calypso is a Real-Money exploration and colonization MMO set on Calypso, a fantasy planet. The base game is free to play and explore, but if players wish to own plots of land or have an easier time to start, they should invest some real money into the game, on which they could even see a profit if managed well, thanks to the game's two-way currency conversion system. The game was originally called Entropia Universe, but the developer team, Mindark renamed it around 2008 or so.
Planet Calypso has no class system; instead players pick up different skills and develop them by use. The game also features deep social, political systems and lots of crafting disciplines. Examples of the latter include players being able to learn different professions and selling these services for others, such as Surgeons who can change a player character's looks. There are combat roles, too, who can supply the other characters with different looted materials and items not available otherwise.
The game is very limited, as most activities, even basic ones such as equipping or un-equipping certain items requires PED, the premium currency in the game to complete. The game also lacks a clear direction, and instead relies on the players to find their own goals in it.