Desktop Game & More

Update - yes you can, if you're building a standalone executable, and no, it does not require Unity Pro. :) Here is a C# example that starts Notepad:

using System;
using System.Diagnostics;
void Start () {
    String path = @"f:\temp\data.txt";
    Process foo = new Process();
    foo.StartInfo.FileName = "Notepad.exe";
    foo.StartInfo.Arguments = path;
    foo.Start();
}

Here's another example that opens a file and writes a line:

using System; using System.IO; using System.Text;

void Start () { String path = @"f:\temp\data.txt"; FileStream bar = File.Create(path); byte[] data = new UTF8Encoding(true).GetBytes(path); bar.Write(data, 0, path.Length); bar.Close(); }

So basically, anything that the the Unity version of .NET can do, a standalone program can do.

[obsolete] No, it's not a stupid question, it would be a nice feature, but... Shoot a crate, launch a virus - Open a door, write a password keylogger file... The possibilities are endless - which is why the possibilities are limited. :) Because it runs in a Browser window, there are security restriction on what Unity can do. Which includes not being able to access files on the local system. (I'm not sure about the standalone executable version).

There's a reference to being able to save player data at: Game External Files.

Also, if you want to learn Unity (possibly starting at the shallow end :), some more Answers are:

Start Learning Unity... and Scripting...

You will be scripting if you want to use Unity. :)

And - please read the FAQ

Update - as Eric5h5 point out, this only applies to a Browser build. If you want to do a stand-alone executable file, then yes, you can do all of those things. Unity has full access to .NET, which means you call open/close files, make system calls, do anything the Win32 API can do.