Maybe. By "not a platform game" do you mean a platformer? I find top-down games easier to make a good plot line for.
Also, this step takes time. I came up with a game concept for myself not too long ago, but didn't have a story line. It a couple weeks for someone to respond.
Last, can you provide a few more details on how you might like the game to be, such as game concepts if you have them?