In the book Joy of Work, Scott Adams (the guy who created Dilbert) wrote:
plagiarism + lack of talent = originality
I think one of the keys to creativity is curiosity have how things look/work/behave (whatever) and the only way of know is I create the thing myself. If I don't create then I'll never know. You also have to have an ability to play and experiment.
One of the things I like about games development is the diverse set of skills required: it's art, it's logic, it's maths and sounds and colour and science. I can't thing of many hobbies or jobs that require such a range of disciplines.
If logic is more your thing, you might want to try is try to create games or demos in pure code. Don't worry about creating any external media and only use vanilla DBPro, no plug-ins. These limitation will help keep you focused. Also, focus on a single aspect of the game or demo, such as player controls, making something move around the screen in an interesting way, creating a random map or whatever it is you're interested in. This links into what KISTech was saying, keep it simple and don't overwhelm yourself.
The other thing to look as is come up with a simple aspect to look at - say a planet orbiting a sun - and try to come up with different ways of achieving the same effect. I've done a lot of engineering design and this is something that gets drummed into you very early on and it really does help with being creative.
Being imaginative is a little trickier to nurture. However, don't be so hard on yourself as most things are derivative and true uniqueness isn't always appreciated. Just be open to ideas and influences, go to art galleries and museums, try and expand the genres of movies, books, games and music you watch, read, play and listen to.
It may be that games development isn't for you but it may be that aspects of the process are. If you like the logic side then create your "geopolitical world simulation game" using text and menus. Turning such a game into a spread sheet is probably closer to how it's done in real life anyway.