Castlevania: Dawn of Sorrow is a platform game with RPG stat-building elements. The player guides Soma Cruz through a large sprawling castle, where he or she has almost free reign to go wherever he or she wishes. However, similar to the Metroid series, certain areas are inaccessible until the player defeats key enemies and obtains critical items. Along the way, the player must defeat a horde of monsters that roam the various rooms of the castle with the weapons he or she finds along the way. The more enemies the player defeats, and the stronger the enemy, the more experience points they get, which enables them to level up and improve their abilities. Several items, including weapons, armor, and accessories, can be found around the castle, dropped by defeated foes, or purchased at Hammer's shop, and can be used to increase the player's statistics.

The game features the "Tactical Soul" system from Aria of Sorrow, where Soma can absorb the soul of an enemy he defeats and can use their power. Dawn of Sorrow improves on the previous system by allowing the player to upgrade most soul abilities by acquiring multiple copies of the same soul. Souls can also be used in weapon synthesis to create rare and powerful weapons.

A new feature, the "Magic Seal" system, makes use of the system's touch screen. Using the DS stylus, the player must draw an intricate pattern known as a magic seal on the touch screen in order to trap defeated boss enemies. If the seal is not drawn correctly, the boss will regenerate some energy and continue to fight. The touch screen can also be used to break certain blocks, navigate menus, select a warp point, and control certain familiars.

The game also has a multiplayer vs. mode, where one player creates a section of the castle, complete with enemies, and both players race to defeat the enemies and reach the end of the level; players are also able to trade souls they've found in the game.

Taken from wiki