krank is a game of dexterity, being somewhere between Breakout and billiard, where the aim of each level is to shove floating stones towards compatible static stones. You control a short chain of stones with your mouse to achieve that.
While the game's visual and audible aural style is as simple as the rules are, there is no shortage of variety. Different level layouts provide enough challenge and different gameplay elements (the interactions between different types of floating stones with different types of static stones) are introduced at a reasonable paste. If you find the hardness curve too flat or simply don't like one level: the game permits you to skip one level ahead the last finished one.
Another important aspect, which keeps me playing, is the variety of look and sound. Each level has it's own pretty background and there are different sound themes, which give a subtle but very effective feedback of what is happening on the game field.
Thorsten Kohnhorst is the programmer behind krank. He created some other games, which I will introduce in the future. Michael Abbing is the game's sound designer. Nine others contributed to the game's level designs.
The game was written in python and packages are available for Mac OS X, Windows and Ubuntu (thanks to Vadi for the latter!) On other systems you will have to make a little fix to play it. The code and media appears to be in the public domain.
If you ever enjoyed a puzzle, billiard, golf or an arcade game before, you definitely should give it a try. Especially with it being so easy to start playing (see package links above.) By the way: I haven't seen a game menu integrated so well in a game since the unfree Psychonauts! The only feature I'm missing is a save function.
Update: Łukasz Krotowski submitted a patch, which makes the game auto-save on GNU/Linux systems. Now I just have to learn how to use patches. ^^
Have a look at the gameplay in the video below but I must warn you that the sound effects (which I am unable to capture) are an important element of the game and that the video (especially with it's visual quality) is a bad representative of the actual game.
krank gameplay video - pardon the lack of sounds :(