Having idea is fun. When developping a game, having the idea is probably the easiest and most fun part of the project. Delivering our ideas into a final product is much harder and demands huge commitments. Here is a simple, beginner's process that can help you get to the end of a production with more ease and focus: Think big, plan low, deliver more.
The process is based on a cyclic approach of expanding and reducing the scope of a project before and during production time. The first step to creating something is to come up with a vision or an idea. This often starts with a brainstorm or a flash of genius. One way or the other, it is time to “think big”. You have to jump in on the idea and explore every aspect of it. You put aside doubts and censorship and throw on paper every possible idea that revolves around the concept, expanding until every little detail has been explored or your brain melts, whichever comes first. Once your brain has melted (because you cannot ever explore every little details of a given idea), it's often a good time to put it down to rest. Come back to it later with a fresh brain and expand it some more.
You will then probably feel like you have a good grasp of the concept. While some may think that production can start once you have that kind of “mental plan” to guide you, it's good to actually pin down the core of the project before doing any actual development. If you do go into development at this point, you are likely to encounter important questions and problems which will slow down production or stop it altogether. In a lot of cases, the work will be a complete waste. This is why you have to “plan low” before starting development.
Go back to your ideas and meditate on this. What do you really want to express? What is the kind of fun that you want in your game? What are the skills you want the player to use? What is the story? The meaning? What is the essential CORE of your game? This is your target: The Core. While you may feel you had tons of great ideas revolving around your concept, they cannot all go together elegantly. You have to take the bloody axe and chop down every unnecessary part until you come up with exactly the smallest possible number of ideas (or mechanics) necessary to your game. Chop it kindly though and put the extra ideas aside for later. They are always a good reference when you want to go back to your initial idea, but for now, they are extra weight. An example from Nintendo's development process: when they developed Mario 64, the first thing they did was make sure that running and jumping was fun (The Core). After all, this is what the player do most of his time in that game. Shrinking down to a “low planning” is just that: finding out what the player will do most of his time and making sure this is fun.
When you understand the basic activity, you can go on and start production. Build a first prototype and see if the core is fun. If it's not fun, then there is a problem and you should fix it before doing anything else. Building on a broken core is always a waste of time. You cannot make a bad cake tastes good with fancy decorations. If you do have a fun prototype, then it's good news. You can test it with some friends and collect comments but be careful; some people don't really understand the concept of “work in progress” and can make destructive comments that might turn you down instead of giving you good insights.
Playing the prototype, you will probably come up with new ideas but sometimes, especially if the prototype comes out to be very fun, you feel like you have yourself a game and might be reluctant to change anything. While you can't make a bad cake tastes good with fancy decorations, you CAN make a good cake better with some sweet topping and a colorful presentation. This is where the extra notes you so “gently” chopped away come in handy.
Digging back into your original notes is sure to vividly bring back old ideas and spark more new ones than you can ever use (always works for me), but at this point, you have a nice prototype to direct the creative process. Now the difficult design process of trial and error begins and you might have to go several routes before finding the one thing that really comes out nicely.
Making games is an art
Design and creativity is a difficult process. Don't be discouraged if your ideas don't work instantly. Making games is essentially an art, and the process of making art, any kind of art, always requires to throw away a certain amount of ideas in order to find the one gem. If this was not the case, it would not be art. It would be craft. And every single game would be the same.