Most Rhythm Games follow a simple premise: The game will flash commands, and you have to input the same. This may sound easy and familiar, but Rhythm is where the trickiness comes in; the commands have to inputted in time with the music, within a certain timing window which varies from game to game. If the input is made too early or too late, the player misses. The size of the timing window can hugely impact the game; for example, both Guitar Hero 3 and Rock Band have one "hit or miss" timing window, but RB's is much smaller, demanding better timing. Some games like Dance Dance Revolution have multiple timing windows, giving the player a different score depending on timing accuracy. To summarize: hitting all the buttons as fast as you can is a surefire way to fail as fast or faster than doing nothing. Traditionally the commands are represented with little markers, such as arrows or gems. Over time, the markers scroll toward a target zone. If the correct input is hit with good timing as the marker passes by the target zone, the marker disappears or blows up indicating success. Missing is usually represented by the marker drifting past the target zone unharmed. This highly involved game of Simon has seen a particular boom in recent years. The actual device used for input also varies; there's the famous Dance Pad, a "buttons on the floor" setup which requires a quite a bit of physical activity on higher levels, then there's plastic versions of musical instruments, actual musical instruments, full-motion cameras, and even *gasp* a regular controller or touch screen. As a game style, they're similar to Bullet Hell, in that they are very much about practice, and often feature extreme difficulty curves with very high skill ceilings, so a wide range of difficulties spanning from Easier Than Easy to Harder Than Hard is the norm. Similarly, Gameplay Grading exists in almost every rhythm game alongside the conventional Life Meter, so perfectionists can differentiate themselves from those with looser playstyles. Like bullet hell, there are (at higher difficulties) countless things flying around the screen in a manner that looks like chaos to the uninitiated. Unlike a Bullet Hell, in which the object is to avoid all those things, you have to catch them all here. Not all rhythm games use a conventional interface of discrete inputs. Singing games usually use lines that go up and down with pitch, with the goal of singing with the same pitch as the line passes through the target zone. A new wave of dancing games have no markers at all, instead providing flashcards and animations to cue the player on what to do. These are usually called "dance games" or similar, but soon may come the day that rhythm games with markers are dubbed "classic rhythm games" to avoid confusion. Because of songs' tendency to repeat a part of themselves, the rhythm equivalent of That One Attack can occur multiple times in the same song. Most full rhythm games (as opposed to Unexpected Gameplay Change rhythm minigames) feature licensed soundtracks. Most companies apply Cultural Translation when bringing the games to the US, serving up a soundtrack of mostly popular hits. Licensing popular music can cost a non-trivial chunk of a game's budget, and in some unfortunate cases, a publisher will try to sell a substandard game based on the song list alone. In rhythm games, Syncing the audio, video, and gameplay altogether is very important, and lag in either the audio or video is very noticeable to long-time rhythm game players, and can frustrate new players as well. Fortunately, modern games have calibration control to make up for this. The small downside to calibration for experienced players is that the TV still won't know if you were successful in hitting a marker until after the fact, so the marker will explode too late and past the target zone, but at least it'll give full points. The downside for casual players is that setting it up is hard, though some games like Rock Band have controllers that have light and sound sensors that attempt to find the calibration for you (fan opinions vary wildly on how accurate these methods are, but for casual play it's usually good enough). Older CRT setups with built-in speakers (or simple speakers with no middle-man device) are the best in this regard, though most don't go so far as to Break Out the Museum Piece since the audio-visual quality is generally lower. Compare Exergaming. The nature of Rhythm Games often evokes the Centipede's Dilemma, even more so than other Action genres. When you can plug your own music collection into a Rhythm Game, you have the unique form of playable crack known as a Music Player Game. Because Rhythm Games often have large varieties of songs, there's bound to be at least one song you really like in many of these sorts of games.
Notable games in this genre: