Too much?

I saw in your other post that you have a long list of ideas. Here's something I do when I feel like I either have too many things spinning at once, or if I feel stalled on my "one big thing" that I'm currently working on ...

Take a few of the ideas that you find the most intriguing and spin a few cycles on each one.

Flesh each out a bit in the manner that Dralius wrote about where you just write out a description in words ... write it up as if you're trying to describe it in a 2 minute conversation with a friend ... don't worry so much about the details on the first pass -- just list the important high-level points of what makes the game interesting.

Then take a second pass at each of the ones that still look interesting to you. Go through each of the high-level points and give some more details on each ... sketch up some diagrams, list out a table of values/relationships, etc.

By the end of the second pass, I usually have something that jumps out at me and says "I'm the one you should work on now" ... and I have a clearer definition on the other ones to come back to later.

While I always seem to have 1-too-many projects in-process at the same time, I seem to have had the best results when I'm able to fully drill-down into a single thing until I get it to a logical stopping point ... maybe the first complete rules draft, or a fully operable prototype, or through the first serious playtest. Then, I either cycle around with it to revise and improve and get back to that previous spot again ... or I let it sit and perculate in my head a bit.

The trick is to focus on getting something all the way through the process.

HTH,
-Matt