Well, I think I have settled on a concept.
The run from one side of the screen to another and get stuff and kill things concept has been done to death. After all, isn't that why we upgraded to 3d?
So I've been trying to decide how to address that. I could make a "Link" (zelda 2) type game where you travel across the planet(s), and go side-scroller for the fighting. Or I could just do side scroller. Or I could do top down. I was trying to figure it out, but then I realized that since this was my first game, it couldn't be overly complicated. Plus, it's often the simple concepts that make the games fun.
Then I was playing Metroid last night. I rolled into the little ball and was going through a little maze they made for me, and it hit me. I can't think of a single game where you roll as a little ball through a side-scrolling puzzle. I could do that.
I was a little worried at first that that was just ripping off Metroid. But then I remembered there is nothing new in the world, and that I was already considering ripping off from tons of games, so what's so different from ripping one little concept off of one game? Plus, it is in no way crucial, or a large part of Metroid. It's just this one little thing that Samus does, and in my game, you would always just be the ball.
Now, I know there is "Super Monkey Ball", but that is 3d and you don't get power ups or anything like that.
This is going to be a 2d maze game where you have to take timing into account to get past shooting fire, get upgrades for your ball (like a magnet function to go along ceilings over spike pits), and calculate speed for jumps/loops/etc. I think I'm going to make it like Metroid, but like how Metroid would be if you never got to stand up.
So, one vast board, no levels. All fully explorable, limited only by which power ups you have. Health bar, upgradeable to earn more health. Hidden items. Score. Monsters. Hazardous environment. Etc... Lot's more to come, but for now, a screenshot!
I'm temporarily calling it "Clink" (dual meanings. The sound a metal ball makes when it hits something, and what some people call a prison, which is what the game is like you are trying to escape), and you will be able to (at the start of the game) choose what color your marble is. I've screen-shotted it with a Samus themed marble in tribute...