The Why is as important as the How

When designing a new feature for a game, one always has to think how it will affect the rest of the game. Games work as wholes, and if you move one part, then everything else is affected. Even simple things, like a new HUD or a new menu system changes the rest of the design.

Propagating all the changes a new decision creates is always a hassle, and sometimes its really tough to keep track of it all. One thing you can do in these cases is to make a list of all the changes a game design will go through. You just start thinking of each system in your game individually (having a list of those also helps ;) ), and start listing all the adjustments that will have to be done.

But, here comes the sweet part, next to each change, you list the reason why you're doing it. This is very, very useful. Not only will you get a clearer picture of how the game is changing, but it will also tell you if your new ideas are truly useful, or just disguised feature creeps. Also, it helps your team understand the rationale behind each decision, and speeds up debate about implementation. I've found that it is much easier to push for a cool new idea if you can show them why its necessary from the get-go.

So there you have it. When adding a feature, don't just make a list of changes, but also of the reasons behind them.