Oh yeah me too. I've always been thinking up game characters and stuff. I have drawings from when I was 5 years old of "Donkey Kong Countree 4: Kiddy Kong's Castle".
One of my ideas that has gone through several changes is called Pandamonium. It's a platformer series I've been thinking up since I was very young. It originally started off as essentially a DKC clone in every way, I even copied the Kong helpers.
It was originally called Chubby the Panda, and the sequel would star his son: Cubby the Panda.
Then sometime later I picked the idea back up, and made it a 3D platformer where you could play as either Chubby the Panda, a tiger, Cubby the Panda, or a turtle, and they would each have different ninja weapons. Then I changed it to all pandas. Chubby became Panic the Panda, Cubby became Jr., the tiger became the huge buff sumo panda named Pummel the Panda, and then there would be the wise master panda, Pow.
One concept I toyed with for a while was using the 12 chinese zodiacs. You would enter your birthday, and each month would be assigned to a chinese Zodiac, and this would determine which character you played as, what weapon you used, and which character was your partner(and what weapon they used). But, I scrapped this idea.
Now I've changed the idea around again. This time you play as Panic the majority of the time, but in certain segments you could play as Panic Jr, Beefy the Badger(replacing Pummel as the huge fat guy, and he has either a chainsaw or an axe), and Greasey the Opposum.
The bad guys would all be big cats, ie. tigers, jaguars, panthers, etc. The Main bad guy would be an evil Samurai Emperor Tiger, who I have yet to come up with a suitable name. One of the lower bosses would be Captain Coyote, who was originally a boss for a separate game starring Greasey the Opposum, but I quit that game and moved both characters to this one. Captain Coyote would look like Napolean, or Captain Crunch in his attire.
Another idea for this game was the concept of your Dragon Guardian. The story goes that every thousand years the Dragons return to our world and they each choose someone to be there protector. Panic is chosen(as well as Beefy and Greasey), but then he is told that not all dragons are good, and that some of them are evil. The Dark Dragon will choose the most evil person they can find to be there protector, and the Dark Dragon chooses that evil Samurai Tiger guy I mentioned. This guy was already an enemy of the Panda Clan, as the Tigers and the Pandas have been fighting for centuries, but now that he has possession of the Dark Dragon, he has crazy evil powers. You and the other chosen ones(Beefy and Greasey) must stop him, blah blah blah, etc.
So anyway, you use this Dragon for all kinds of purposes and tasks.