How long would it take to make a 2d game?

Hi, I'm going to be a junior in high school , and wanted to make a 2d game with a storyline(that would maybe take like 3 hours to beat) in about 3 months with an end goal of getting it greenlit(I know its not probable, but it would be a motivation to make me finish the project). For my programming experience, I've done simple side projects, I'm a lead programmer on the robotics team, and currently have an internship under a professor. In unity, all i've done( and this was like 5 months ago) is get one floor and a sprite that jumps around with sound when it hits the ground, and a jupming and running animation. About how long would take me with no help(worst casinario) to build a 2d game with a story and music( I don't know exactly what I want to make, so I'm not sure of the complexity of the game). I make music on fruity loops, but would have have to learn the best way to make sprites in adobe illustrator(or i might try to find someone online to help).