Atmosphir is a game created by Minor Studios that allows the creation of the scenarios by the players themselves. The game has several tools for creating games platform the way you always thought, and has gone out of its Beta phase. Need not know anything about game design to begin to develop. Anyone can create their own ground.
In addition to creating its own ground to play, you can still choose from other people, because scenarios can be shared. After setting up your game you can send it to site to share it with other members. You can make the evaluation of each scenario, giving notes on the difficulty and give your feedback directly through comments.
To begin to create and play, no need to register. But if you want to have your name in the rankings, customize your avatar, collect points, you must login. Moreover, without the login you will be able to do design But not to share.
The scenario development tool is simple and offers many features such as various types of floors, platforms, treasures, power, flags, bridges, enemies, decor and even music. After creating you can also set up rules. All this can be done in your browser, without needing anything else.
You can play alone or in multiplayer mode. It is an interesting tool because it enables the creation and sharing of user game easily enough.