Cytus is a mobile rhytm game supported by Android, iOS and even PlayStation Vita. There's a "free to play" version, it limits you to 13 chapters and a 30 seconds cooldown before starting a chart (song). If you buy the full version, the cooldown will be removed and you'll have access to more chapters exclusive to the full version.

Gameplay

This game can be very challenging. With its simple gameplay, yet ridiculous possibilities, it can satisfy a lot of hardcore gamers. There are even hidden charts you acces by interacting with the background before starting the chart.
You tap notes as the scan line passes. There are 3 types of notes:

Click Notes

You have to tap on them while the line is one them for a perfect. For a good you can be slightly off, for a bad you... well, need to time it bad. And for a miss you have to ignore them.

Hold Notes

They work just like click notes, but you must hold them until they disappear.

Drag Notes

You must drag them without interruptions along the "rail" until they disappear.

Score System

D

This is the fail result, you get it if you don't score at least 700000 points.

C

A bronze score you need 700000-799999 points for.

B

Some kind of grayish silver. 800000-899999 points.

A

Pure silver. 900000-949999 points.

S

Gold. 950000-999999 points.

MM (Million Master)

If you don't make a single mistake during the chart and get all notes perfect, you will score 1000000 points and get a medal with the words "Master Cytus".

Soundtrack

There is a large variety of music in this game from many genres.

Story

In the distant future, the only sentient beings in the world are robots.

They are the last remnant of the human spirit.

However, mankind is not dead.

Technology exists that is capable of transferring memories to these robots.

But with limited space, new memories will gradually overwrite the old.

To prevent the emotions in human memories from fading away, the robots resorted to converting the emotions to music, and storing them in a place called Cytus.

The robots use these songs to experience human emotion and dream that souls exists in each of them...

There is not much story to the game aside from the description, but the chapters seem to have a cryptic way of telling one story or more.

Difficulty

The game has difficulty levels from 1-9, they differ in each chart and do not get progressively harder with a pattern, some are easier, some are harder. However, there is also a hard mode you can switch to, it increases the difficulty for every chart.