HammerMT3 is an online computer game set in the Ancient East. In this game, the three kingdoms – Jinno, Chunjo, and Shinsoo - have been ruled by the Dragon God. The Dragon God has watched over these three kingdoms for as long as there have been settlers there. Because of that, the kingdoms have enjoyed peace for hundreds of years. However, Metin Stones have mysteriously landed in the kingdoms and caused destruction and chaos. The kingdoms now wage war against the others. The animals have become monsters, and the dead been brought back to life as evil undead. The player must ally himself with the Dragon God to defeat those that have been transformed by the Metin Stones and restore order to the three kingdoms.
As an MMORPG, Hammer MT3 has multiple users playing the game on the Internet. Players can interact with each other, form groups amongst themselves, trade, and battle. At the start, the player can choose what kingdom he wishes to be part of. Battles take place on the ground, with the characters fighting on foot or while riding horses. Guilds can be formed in the game. When a guild is formed, the player can become the castle lord, with the castle itself becoming a fortress after being upgraded.