Proposed modifications:

1) Create 3 unique levels (with unique objectives) connected by a story

2) Add new powerups affecting gameplay

3) Create a new final boss (likely with existing sprite but with new enemy behavior)

Credits:

Tutorial and assets provided by Michigan State University

Created by Raduan Moustafhim

Download

moustafh-Windows.zip 31 MB

moustafh-MacOS.zip

Comments

I like your proposed modifications, good work! A couple of comments:

As a tip, when making new levels, try to make sure that they're significant and unique/different from others in some shape or form. Adding new enemy types, challenges, or obstacles can help with this!
What are you planning that your new powerup do?
What types of behavior do you think that you'll add for your new final boss?