(First off, I apologise if my blogs still sound little wooden, I'm learning some of this stuff on the spot, so, sorry.)
I guess, if you think about it, all types of games are similar in some way. You're always trying to win, finish or survive a game no matter what shape or form, it's just the design that varies.
There are so many aspects involved with game design, it's hard not to just make a big list.
So, to start from somewhere logical, you need an idea (a realistic one). Game design is the process of creating and refining this idea through communication with everyone involved. This will normally begin with a design document - a guide to work from - which will be constantly changing throughout the process.
All limitations will need to be taken into account, as well as genre, narrative, gamepl-- see, I'm starting to list now, gawd.
Ok. You catch my drift anyway, It's all about teamwork and constant reviewing, play-testing, changing, refining etc. To make a game successful, all of these aspects need to come together seamlessly and effectively, and most of all it needs to be fun. That's the whole point to games, isn't it? A form of entertainment, fun beyond all else.
Gameplay/game mechanics are an important factor in making a game fun - how you interact with the environment, how your character moves around, how the UI works and so on. It's all just about trying to outdo one another really, and pushing boundaries opens up new avenues to explore.
Every game company knows that innovation & originality could produce great things but a lot of them aren't willing to invest the time and effort, or just simply can't. Again, money is a factor that can't be ignored. Maybe if we lived forever and money grew on trees, things would be a little different, maybe not economically sound, but different.
http://www.girlsgogames.co.uk/ - I'm quite speechless, I mean honestly.