Inspiration

The first thing you'll want to do is come up with an idea, which you probably have, since you bothered to look into making games in the first place! Aha!
A good rule when coming up with anything is that if you think of it, someone else has probably already thought of it first.
Never go with your first idea. Chances are it won't be as original as you think. Instead, work on it, change it, add to it. I'm not saying that you have to throw away your idea, just play with it, and make it your own.
A good example of an idea not being fleshed out enough would be the space janitor thing. I can think of at least two separate game series that use this. If only the author would have sat down and worked on his idea a bit, he wouldn't have looked like such an unoriginal fool.
...
Anyways, I think you get the point. Don't go with your first instincts. Developing your ideas will lead to much more interesting characters, scenarios, and puzzles.
So what do you do if you can't even come up with that initial concept? Brainstorm.

Brainstorming is awesome. I guarantee that if you do it properly you will surprise yourself. The trick is learning how to avoid censoring yourself, which can be harder than it seems.
We learn at an early age to censor ourselves:

• "Don't do that, it's rude."
• "Don't say that, it's not nice."
• "Don't do that, or you won't be cool and girls will hate you forever."

Now is the time to be a rude, not nice, uncool person. No one is going to see this stuff, so let it all hang out, whoo!
Brainstorming is all about going nuts. It's about putting down on paper every single idea that pops into your head, even the stuff that makes no sense.
Rabbit, flanger, fork, eat, crow, mangle, fishbone, soup, car, head, laser, dingle.

See? That's brainstorming.
Now we already have some ideas there. How about a game involving a missing rabbit carved out of fish bone with a laser, stolen by a maniac with a penchant for crow soup?
Obviously that idea could still be fleshed out a bit, but I highly doubt that it has been done before.
This works with drawings too. I do a lot of doodling. A lot. Enough that I even put up a website with some. Doodling is the ultimate release for me. I just let my hand go and whatever comes out, well, it's out. A lot of my favorite characters were invented that way (Earwig and the Welcome Mutant for example).

Whatever method works for you, go with it. There are a lot more brainstorming techniques out there, so go ahead and load up Google and find some. It'll change the way you create.

Story

1. Outline

   So now you've got your one of a kind idea. Now what?
   Now you come up with the story.
   First you'll want to make an outline. This will have all the basic plot points and crap. Basically all the important stuff that happens in the story, without all the details.

   • Barney the frog wakes up in a closet, dazed and confused.
   • Barney is in the university, he wanders the halls until he meets Jojo, who tells him about Dr. Doodoo's plan for destruction.
   • Barney goes home to get his trusty hat and discovers that it has been stolen, he vows revenge.
   • Barney takes a plane to Madagascar to infiltrate Dr. Doodoo's secret lair.
   • Barney is captured and put in a prison cell, where he meets the beautiful Molinda, then he escapes using magic.
   • Barney confronts Doodoo in his secret lair and kills him with a saw blade.
   • Barney and Molinda get married and "do it".

   This will make it easier to add or change things, and will help you immensely when it comes time to actually write the story.
   Which you will do now.
   I don't know what to say here. Writing is an art that baffles me. Good luck!
   Ha ha.
   No, seriously, you aren't trying to write the next Bible or anything. Just fill in the blanks, add the details and minor characters, that kind of thing.
   One thing to point out is that you aren't concentrating on puzzles yet. There will be plenty of time for that hell later.

2. Filling it in

   • Building Stronger Themes: What type of themes, story elements, etc. you want to play at.

3. The Characters

   • Character Creation Form: Useful in bringing the character to life.
   • Creating an Original Character
   • Making Villians
   • Also, if you are making a game set in the times of 'thous' and 'thees', make sure you get them right!
     Getting the Thous and Thees right

4. Puzzles

   The story has been written. You're in over your head now, no turning back. It is time. Time for the puzzles.
   Puzzles are what make them games and not just stories where you can walk around, which would probably be pretty cool too.
   There are a billion philosophies on puzzle design, and I am not the person to debate them, because I'm lazy and not perfect.
   Suffice it to say that "Use Key in Keyhole" is not a puzzle, and "Balance plate of boiling frogs on head to unlock door" is also not a puzzle, although it would be hilarious if properly animated. Point is, don't be too obvious, but don't be too bizarre and obscure either. Also, clues are a must. The player has to somehow make a connection between "doing this" and "achieving that".

   Here's an interesting example:
   In the uber-classic "Monkey Island 2" there is a puzzle involving a pipe that has to be opened. There's a big bolt on it. The player at some point will have in his or her inventory a frozen monkey with it's arms in an odd position.
   To some people in the world this was funny, because the monkey could obviously be used as a "monkey wrench" to turn the bolt. There was a cultural connection, and no in-game clues were needed.
   To the rest of the world however, "monkey wrenches" aren't called "monkey wrenches" at all. No no. They are called "Spanners", or something else. I haven't looked into it much. Obviously this puzzle didn't make much sense to those people.

   Puzzles above anything else, are something that you will get better at with experience. You'll learn what kinds of things work, and what kinds of things will get your inbox swamped with confused emails. There is no perfect formula.
   So how do you get started?
   Well, first of all you have to identify and/or create some problems for your player. Go through your story and find the major obstacles that the main character faces. Once those are found you can start making life miserable for the player by breaking those obstacles down into even more little obstacles. Teehee!
   Here's what I mean. Let's use The Adventures of Barney the Frog as an example:

   Barney has discovered that his trusty hat has been stolen by Dr.Doodoo.
   Grrrr! That makes him mad!
   Somehow he has to get to Madagascar to get his revenge!

   Bing! Major obstacle!
   The first part of the game will be Barney trying to make his way to Madagascar. That's the major problem/puzzle that the player faces.

   Barney goes to the airport but discovers that a plane ticket will cost him 100$, and that he will need a passport. Poobungies. Barney has no passport, and he left all his money in his hat. What will he do?

   Aha! There's two more!
   See what I did there? I broke the major problem down into two smaller ones. This can go on forever.

   Barney finds a shifty looking thug in an alley. The thug can get him a passport, but it will cost him four pounds of grandma's cookies and a loaf of turnip bread.
   Barney has also found a woman willing to pay him 100$ to cut her lawn, but her lawnmower is broken. It needs a new wheel and blade.

   You could make an entire game just about trying to get on the plane to Madagascar. It's all about breaking down and splitting obstacles, like some crazy get-rich-quick pyramid scheme your uncle relentlessly tried to push on your father until he ended up with a broken nose.

   There are also different types of puzzles. There are the obvious inventory puzzles, where you have to "get this to do that". There are combination puzzles, where objects have to be combined to create new objects.There are logic puzzles (A-la "Castle of Dr.Brain"), timed puzzles, etc...
   I can't name them all. I just pulled those out of my butt. You see what I mean though.

5. Dialogue

   • Description, Dialogue & Action: The Action portion might not be all that useful for a game, but you can make use of the help on descriptions and dialogues.

Art

The art in your game would be made up of basically 2 parts. The characters, and the backgrounds. However, you wouldn't get very far into this if you didn't know some basics.

The Basics

• Light and Dark
• Colourising

The Characters

It would be a good idea to learn some basics of human anatomy, even if they might not be completely visible in-game, as it helps give volume to your character:

• Human proportions
• Human muscle anatomy

After that, you'd want to draw the actual parts of the body:

• Drawing heads
• Drawing hands
• More drawing hands
• Designing Hair

You'd probably want to pay attention to skin tones as well:

• Skin Tones
• Skin Tones 2

And to give you something to put it all together:

• Tutorial for a hi-res cartoony character
• Drawing a character from a scanned image
• Drawing a character from a photograph

Once that is complete, it is time to start animating:

• Animating a sprite
• Easing in and out

Of course, the most basic animation is the walk-cycle:

• Walk-Cycle Tutorial 1
• Walk-Cycle Tutorial 2
• Walk-Cycle Tutorial 3
• Walk-Cycle Tutorial 4
• Walk-Cycle Reference

The Backgrounds

First off, the basics. You'll probably need to know about the basics of perspective.

• 1 & 2 point perspective
• Spherical Perspective

Now then, what resolution are you going for?

• Hi-Res Tutorial by MrColossal
• Lo-Res Tutorial by MrColossal

You might want to copy another style exactly. I wouldn't think this would be the best of ideas, but whatever, you may have your reasons. Anyhow, these tutorials may also be useful to pick up points to help you develop your own style:

• You know the Indiana Jones adventure games? They were pretty popular, and some people like the idea of doing remakes or sequels:
  • Indy & the Last Crusade Style BGs: An almost exact copy tutorial
  • Indy & Fate of Atlantis Catacombs Style BGs: An almost exact copying tutorial.
  • Indy & Fate of Atlantis Style BGs: Helpful for picking up points for your own style.
• You remember the MAGS game "Buccaneer"? It had some very pretty art. The creator made a tutorial for emulating the background style:
  • Buccaneer Style BGs

Perhaps there is a specific style you want to learn about?

• AGI Styled BGs
• Cartoonly Styled BGs

Or maybe you need help with a specific part of the background?

• Making a star field
• Painting Clouds

Here are some more background tutorials:

• Tutorial by Big Brother
• Tutorial by InCreator

Hey, you might not care about making the backgrounds look extra pretty in sacrifice of time spent on the rest of the game! In that case, you'd want:

• InstaGame BGs by MrColossal
• Consistent and Speedy BGs by aussie

Programming

Uptil now, what I've said could be used to make a game using any engine/language you wanted. However, since this is a tutorial compilation for AGS, I'll only be talking about it. AGS is being updated constantly, so tutorials get old and obsolete really fast.

• Beginners' FAQ: A good place, where you can assume to be having up-to-date information about beginner scripting in AGS.

Music

Unfortunately, this section is severly lacking. If you know of any good general game-music making tutorials (or are willing to write one in exchange for my eternal thanks), especially at the basic know-nothing-about-music level, please contact me. In the mean time, here is a tutorial for getting started with Anvil Studio:

• Making MIDI Music