Video game making software?

I have planned to design a video game since I was in 6th grade, and I have thought up many great ideas; however, I could never find a program to allow me to create them. I'm looking for something to allow me to make a side-scrolling action game, like Megaman. I am currently experimenting with RPG Maker VX, but it's not at all what I am looking for. So can anyone tell me what software I can use?