You can write and run Scala scripts directly from IntelliJ IDEA. Here's a simple step-by-step guide on this:

1. Create a blank .scala file.
2. Type some code that makes sense using an intelligent, code-aware editor.

   You can also use shell-style comments in this file if you plan running this script directly from your OS command prompt.

3. Run your script with a simple Ctrl+Shift+F10 shortcut to see results in console.