A game apparatus includes a CPU, and the CPU executes a game process. When a player character encounters an enemy character in a game world, a battle screen is displayed on a monitor. On the battle screen, an input pattern is displayed, and background music (BGM) is output from a speaker. A player determines an operation timing based on the input pattern and the BGM (drum part). If there is a high level of coincidence between the operation timing by the player and a timing of the music pattern, damage which the player character applies to the enemy character and experienced obtained by the player character increases.