Syntensity uses JavaScript to script the game logic. This has the benefits of being fast (we use Google V8), is a well-known language, and capable of being carefully sandboxed.

To get started with scripting, see the tutorial (the link is directly to the source code repo - click on 'download file' there to get the tutorial as HTML).

JavaScript - the Language

For a general overview of JavaScript, we recommend:

• Tthe Mozilla Developer Center's Re-Introduction to JavaScript
• Crockford's JavaScript: The Good Parts
• Wikipedia's page on JavaScript syntax
  

Note that these assume you already know about programming in general. If you don't, there are plenty of good tutorials online, but note that most such tutorials for JavaScript are focused on web development using JavaScript, so they teach all the web stuff like working with HTML, etc., which isn't relevant to Syntensity scripts.