Quoted from GameSpot
SUN is a fairly unusual online role-playing game, and it's based on the idea of combat rather than exploration. In the game, you'll undertake missions on huge levels, and if you win the mission, you unlock it for future use for hunting missions, competitive hunting missions, and player-versus-player battles. The game has a fantasy theme, and its look is heavily influenced by Asian anime.
Got my own free sample DVD of S.U.N Online by Cubizone Malaysia. Might try it out to test it's gameplay and system.