Here's one way to make an adventure game:

Write a Story

The first thing you will need, obviously, is a nice short story. If you don't have a story to tell, there's not much point in making an adventure game!

I'm sure there are lots of resources on the internet to help with this stage, but there is no substitute for pure determination.

Create Storyboards

The storyboard is where the important design decisions are hashed out. It mainly concerns the game's plot, characters, and all those infamous adventure game puzzles.

Creating a storyboard for an adventure game is a real challenge, because often the order of events is non-linear. Luckily, there is a trick to designing anything with complexity: break it up into smaller parts. And if those parts are still too complex to visualize, slice them up again.

Create a main sequence of events that corresponds the game's story. Then devise sub-quests in each part. Many of these sub-quests may be inter-related. In the game's logic, this is expressed through the use of variables and inventory items. So be sure to jot down notes about such things.

The problem is how to write all this down clearly so you can understand it later. Drawing a graph on a huge sheet of paper with lots of lines and boxes might be a good method. But there are as many different ways as there are people. Just do what works for you.

Make a Map

Although the storyboard is the abstract map of the game's flow through time, there must be a physical map of the world as well. This world is like the player's interface to the story.

The map should include notes about variables and counts that figure into the game's flow, as well as where flags are set and where items are found and used. The map and storyboard must compliment each other, because neither has all the necessary information alone.

Draw Placeholder Artwork

It is too early to spend time drawing your game's final artwork, because you still don't have any way to play-test your game. You might easily decide to change something down the line. So just draw a quick sketch of each scene.

Also draw a few characters and inventory items. It doesn't matter how they look, a little smiley face will do just fine for now.

Start Coding

Once you have at least a sloppy rendition of each scene, you can start writing code to link them all together. This is where the game really starts to take shape and all that hard work begins to pay off.

After you can walk around from one scene to the next, add the people. Be careful not to get too detailed at this point. Start with the major characters and objects, and work down to the minor ones. Leave out details like flowing water and animation sequences are not significant to the flow of the game. Otherwise you might get lost in the confusion. (Later, when it is time to add finishing touches, you can put them in a separate script file so the main actions remain quickly accessible.)

If there is something wrong with the design, it is not to late to fix it. Just revise your design specs (storyboard and map) and re-adjust the scripts and artwork. Once you are happy with the game, continue to the next step.

Produce the Artwork

It isn't called art-work for nothing. This is one of the most difficult and time-consuming parts of the game's production.

I think everyone has the ability to be a great artist. Unfortunately, few have had the insentive to practice. If you don't have the time or desire to do it yourself, you do have a bit of inspirational bargaining material on your hands.

Most artists would not waste their time when someone asks "will you do the graphics for my game?" because the vast majority of people who ask never finish. But since your game is almost done, what better opportinity is there for a talented artists without experience to get recognized? An adventure game would make a worthy addition to any portfolio! The same goes for musicians [*].

After the final art is complete, you can tweak the mouse-clickable regions to fit, create the paths that determine where the player can walk, and draw the zbuffers that mask what the player walks in front and behind.

Fill-in the Details

Now that the game is playable, you can smooth off the rough edges. Here are some things you can do to make your world a nicer place to visit:

 Add background animations, such as splashing water, jumping fish, flickering torches, blinking lights, wildlife, and whatever else is appropriate for your game.

 Add more speech and conversation with branching dialogs. As long as the dialog stays interesting and lends itself to the game, it makes a nice addition. Just don't go overboard, or the player might get bored with all the talk.

 Interject animations such as facial movements and body language.

 Record the speech.

 Add music and sound effects.

 Create responses for silly things the player might try by handling more events.