The repo for the language can be found on GitHub: https://github.com/jcubic/gaiman the only documentation so far is the Wiki with [Reference manual][1] and [examples directory][2].
And playground can be found at gaiman.js.org. There is proper tutorial on my TODO list. I've created a game for it (guess the number) that is only 31 lines of code (with empty lines), I've added it to [git][3].
On my road map there is also node.js version, so you will be able to run your apps in the terminal.
[1]: https://github.com/jcubic/gaiman/wiki/Reference-Manual
[2]: https://github.com/jcubic/gaiman/tree/master/examples
[3]: https://github.com/jcubic/gaiman/blob/master/examples/guess_the_number.gs