You can create your very own content in Peria. Alone, with Friends or together as Guild/Community. So far the following features have been confirmed:
-Several terrain variations like gras landscape, desert, underworld.
-You can pretty much adjust everything. You can create mountains, caves, tunnels etc.
-You can build all sorts of buildings like Houses, Shops, Tower, Castles.
-Technical knowledge is an advantage. By combining specific elements you can craft elevators and automatic doors for example.
-You can set your own rules in your village for the Economy, Law etc.
-You can create your own Quests and Missions. Not confirmed yet but probably dungeons too.