Tranquility is a game.
Definitely not a regular game. It is more of an abstract visual extravaganza.
It is really hard to explain what it is like, but I’ll try anyway, so here goes…
You are playing above a floor which is just floating in space and your main goal is to hit an object called a spinner.
This spinner is sometimes hidden. Sometimes it is stationary and sometimes it is moving —alone or as part of a formation.
A formation? Yes, there are other objects in this world, and they are platforms.
The spinner is always floating in the air and you need to get high enough so that you can it in order to advance to the next level.
The way you get high is to jump up from the ground and try to land on a platform which makes you jump higher, hopefully into another platform which will give you a boost higher and so on.
There is gravity, of course, so coming down is never a problem, but you do take some time falling down and you can accelerate forward, backwards and you can turn to the left or to the right.
So you just have to hit the spinner and that ends the level (and also gives you a big boost up which may be very welcome if the next level’s spinner is higher up then you are).
Now the secret of this game (from what I’ve seen and I only found out about it today) is to move the mouse (yes, it is mouse-controled) very little and very smoothly and to basically let yourself float around and go with the flow.
Now there is, of course, more to it than that, this are just the bare basics.
For example, the geometry (the collection of platforms of different shapes and their arrangement) is different for every level of every game, there is some background music which is AI generated in order to accommodate to your level and playing type, and there are some really beautiful moments when you get on a higher level and just jump really high and get to see the full level from the air.
All in all a very compelling (if strange) game.
Oh, and it runs on Mac (OS 9 and OS X), Windows and Linux which shows great foresight from the game designers.