Dungeon Hearts is a side-scrolling mash up of RPG and match-three puzzle game elements. The game challenges players to make matches of three or more like-colored symbols (called Chargers or Runes) to cause damage to their opponents. Players can also destroy the enemy's gray tiles, thus eliminating the enemy's ability to attack.
Dungeon Hearts offers a lengthy series of battles, one right after the other, challenging the player to get as far as they can before eventually failing (or beating the game). The game is played by dragging circular discs called Chargers up, down, left, and right along the four lines of the Fatestream. When three like-colored Chargers are touching, the player can click on the group to form an attack gem. This attack gem can then be clicked on to activate an attack using the player character of the same color.
Attacks are handled automatically, as the player controls the discs, and not the four actual characters (a mage, healer, knight, etc.). The more like-colored symbols the player lines up before destroying an attack gem, the more combo points will be added to the attack power. For instance, creating a yellow attack gem, and then dragging that attack gem next to one or more regular yellow chargers (located either to the left / right, or above / below the attack gem) will result in more damage being sent to the opponent than if the attack gem were left alone when activated.
Similarly, attack gems that are placed in the same row or column as other attack gems will also cause combo points to be added to the player's damage multiplier, as seen below.
While creating attack gems allows players to cause damage to their opponents, enemy attack gems and gray chargers will also appear at random on the Fatestream. The same rules apply for combo points for these gray chargers, with gray attack gems (and damage multiplying chargers) being activated if they're allowed to cross the edge of the Fatestream on the far left side of the screen.
To destroy these items, players must activate an attack gem in the same row or column as they gray gems or chargers. Like the player's colored discs, these gray items can also be dragged around to create combos or simply delay the enemy's attack if an attack gem can't be created at that particular time. Using the right amount of skill, patience, and even luck, players can beat enemies without ever taking damage.
As battles progress, more unique discs are added to the Fatestream, with many making the game more challenging for the player. Some will cause player characters to become poisoned, while others will simply lower their defenses. Eventually, symbols will become doubled, requiring multiple attacks to destroy.
In between battles, players are given the chance to level up their four characters by rapidly making matches with like-colored stars in the same way that they would match chargers during proper levels. There are a very limited number of available stars in each of these sequences, so only a few levels are available to earn per character, per stage.
Levels are represented by the numbered stars at the bottom of the screen. As player characters reach certain levels (10, 20, 30, and so on) powers will become available that provide both defensive and offensive capabilities. The blue healing character, for instance, has powers that can bring a fallen hero back to life, or can simply regenerate the HP or all four characters over a short period of time. The red character, meanwhile, offers attack powers that cause large amounts of damage to the current enemy, which can be boosted by the proper timing of clicks by the player.