Many things set Auditorium apart from most in-browser Flash games. For one, its free version is billed as a demo, and you can buy the full version for $10 for over 70 levels and some extra features (pricing is in US Dollars). There is also a version for the iPhone. However, the free Flash version is very playable, and could keep you engaged for hours.
At the beginning of a level, Auditorium presents you with a dark playing field on which you can see one or more containers, several controls, and a flow of radiant particles emanating from somewhere in a straight line. There is no sound. The controls impact the direction of the flow, and you need to slide them around using the mouse so that the flow shifts and fills up the containers. Once a container begins filling up, it starts playing a loop of music. If there are several containers, they each play a different part of the same overarching tune. This way, once they all fill up, you get to enjoy the complete soundscape for the level. In other words, you are creating the game's soundtrack as you go along--"playing" in both senses of the word. See also: Group test: what's the best game for PC?
Every control does something different: Auditorium's directional controls divert the flow left, right, up, or down; an Attract control pulls the flow in and makes it swirl around it, and so on. You don't get to use them all on every level: At first, you will only get two or three directional controls. As you advance in the game, more and more controls are added into the mix. Each control looks like a circle, with a large icon at the centre, surrounded by a thin ring at a distance. You can pull the ring out to extend the control's range, or push it in for a more close-range impact.
Auditorium's containers do not fill permanently: Particles must keep coming in to the container for it to remain full. If the flow is diverted away, the container will remain full for a moment, and will then rapidly deplete and become silent.
With the addition of colour, Auditorium quickly grows more complicated: Some goals can only be filled with particles of a certain colour. To fill those, you must direct the flow so that it first passes through a "colour sphere" and changes colour, and only then hits the goal.
There isn't a single correct solution for every Auditorium level. There are no timers, no enemies, and no "lives." The game is very freeform, and is all about sliding and sizing the controls until you hit a combination that works. Often, there can be interesting interactions between different controls, and slightly shifting one control can make a big impact on the eventual route the particle flow makes. See all: PC Advisor software downloads
One interesting interface choice is the omission of the Pause and Mute buttons. Since any sound in the game is created by your actions, you can easily direct the flow so that it doesn't hit any containers, effectively muting the game. You won't finish the level this way, but it won't make a new sound, either. Sadly, this means you can't play the game with Pandora or another browser-based music service in the background. A Pause button is not necessary because you can simply leave the game be and switch to another tab at any time: Nothing will happen that you don't control directly. If it's making a sound, it will hold that note—so if you're leaving for lunch, you will probably want to leave the game before heading out.