You can download my free RPGs, Kapow! The Super RPG, and Argh! The Supernatural RPG from my publisher page at . They both use the same basic system, called SFX!, with certain tweaks to make them better fit the genre. SFX! is made with the very specific goal of making what players say as they play sound more like how they would describe a scene from a book or movie in the genre, and making sure the outcomes are a good fit to the genre being played.
Check them out! I'd be happy to answer any questions