Tao's Adventure follows a very straightforward dungeon-combat system. The majority of the game is spent in the Monster Tower, which consists of 60 floors. Tao ventures through these floors, finding monster eggs and monsters as he goes. While Tao can move free range normally, once an enemy is in sight the game changes its movement system. From here, every action uses 1 turn. For ever step that Tao takes or spell that he casts, the enemy is allowed one move also. Players are able to cast spells using the DS touch screen, by drawing runes.
Source: Wikipedia, "Tao's Adventure: Curse of the Demon Seal", available under the CC-BY-SA License.