A good intro guide for making a game: http://www.sortingh.at/

Other stuff that I personally like to mess around with:

• Icosa http://forum.makega.me/t/icosa-art-creation-toy-wi...
• Hexels http://www.marmoset.co/hexels
• Construct https://www.scirra.com/construct2
• Pico-8 http://www.lexaloffle.com/pico-8.php
• Actual paper, pens and glue
• Random junk I found in the street
• Knives

I would suggest Godot Engine, too: https://godotengine.org/

Thanks Hairic! What level of experience should someone have to be able to use Godot engine straight away?

Game-Creation Tool <> Scripting/Programming Language

• GameMakerStudio - Drag & drop or GameMakerLanguage
• Ren'py - Python/Similar to Python
• Unity3D (5) - Unity/Javascript & C#
• Stencyl - Drag & drop or Haxe

• Acorn - OS X
• Paintbrush - OS X
• Gimp - OS X, Linux, Windows
• Paint.Net - Windows

• FL Studio
• Garage Band
• FamiTracker
• BFXR
• Audacity (music editing software)

• Unity3D - Unity Learn (on the Unity3D website)
• HTML/JS/CSS - W3-Schools.com
• GameMakerStudio - ShaunSpalding (Youtube Channel)
• Ren'py - Ren'py Website & Maddy E (Youtube Channel)
• Stencyl - Stencyl provides good sources for learning

Please don't be offended if a tool/software/language which you think should be here isn't, these are just a few tools & resources which I'm familiar with which are suited for both beginners & intermediates (and advanced).

Godot utilizes GDscript, which is a scripting language reminiscent of Python. It needs some basic knowledge of programming and a bit of knowing the tools of the editor. There are few tutorial that explains the workflow of the editor.

Overall I would say it's suited more to intermediates, not quite for beginners.