Tribute Games recently dropped this reveal trailer for their new project, Mercenary Kings, a 2D side-scrolling shooter in the vein of Metal Slug with what looks to be a deep weapon building system. Described on YouTube as being in an early prototype stage, there's no information regarding platforms as of yet and there's not too much to go on, other than Paul Robertson's contributions in the animation department (which pretty much guarantees a sale from me regardless of the product).
I loved Wizorb, Tribute's last title, because of how it created depth and complexity in one of the oldest types of videogame, block-breaking games, by cherry-picking elements from the action and RPG genres to create something fresh. This trailer suggests that they might be capable of doing the same thing with 2D platform shooters. I'm totally prepared to let them take their time and flesh it out. You don't want to rush a thing like this.