Some questions for unity+C#

The function GetMouseButtonDown() returns true as long as the button is down, which may be an instant or may be many seconds. If the user clicks very quickly you might not happen to probe the button state during that moment. Use it for long term button holding. EDIT: Sorry, should have double-checked the docs as this is For Beginners and getting things right is important.. There is the similarly named GetMouseButton() that returns true as long as the mouse button is held.

If you're looking for a click event, try OnClick().

For item 2, consider either replacing the text directly if it is actual text, or possibly creating several assets and using SetActive() to turn on and off the ones you need. Using complete levels and adding scenes to your world is a slow and major operation.

For item 3, the pattern we've used on the games I've worked on is to load a front-end scene with menus and such, which in turn selects the data to load. Then you need a way to load and save your data, such as the one described here in their official training videos.

Your code has a bug in it:

void Update () {
        if (Input.GetMouseButtonDown(0)) ;
        Debug.Log("Pressed left mouse.");

}

void Update ()
{
    if (Input.GetMouseButtonDown(0))
    {
        Debug.Log("Pressed left mouse.");
    }
}

In Unity : https://docs.unity3d.com/ScriptReference/Input.GetMouseButtonDown.html

The documentation says:

"You need to call this function from the Update function, since the state gets reset each frame. It will not return true until the user has released the mouse button and pressed it again. button values are 0 for left button, 1 for right button, 2 for the middle button."

Here is a tutorial from Unity on persistent data and serialization: https://unity3d.com/learn/tutorials/topics/scripting/persistence-saving-and-loading-data

PlayerPrefs is an option as was mentioned. The documentation is here: https://docs.unity3d.com/ScriptReference/PlayerPrefs.html . This is simpler, but I am not crazy about the:

"On Windows, PlayerPrefs are stored in the registry under HKCU\Software\[company name]\[product name] key, where company and product names are the names set up in Project Settings."

I personally don't really like games that have to mess around with my registry. Also I might be wrong, but it seems like player prefs if they are being stored in the registry with just a project name key are not going to be able to support multiple save files or the ability to migrate/back up the save files easily.

Personally I would probably be more inclined to use JSON serialization: https://docs.unity3d.com/Manual/JSONSerialization.html Although binary serialization can have a smaller file size at the expense of human readability (which for a save file you might not want it to be human readable anyway).

Sorry, should have double checked the docs. Editing my earlier post.

Alright, thanks for the info lads, i can work with this :)

Additionally, GetMouseButtonUp is the traditional way that UI tends to work. For example, all the buttons on this forum work only on the mouse button being released, not pressed. Granted OnClick will handle this for you.

If you want to get technical, a click is traditionally only registered when the mouse goes down on a widget and then is on the same widget when it goes up. Browser buttons are actually a bit more strict in this regard depending on how they're implemented. For example, if the button goes down over the text on the button and you move the mouse you start dragging the link and you lose the button activation.