My proposed modifications are,

1) Creating a complete, interesting, comprehensive, and coherent level.

2) Add new enemies with their own behavior and 

3) Creat their arts and animation.

4) Add multiple additional levels and tie them in to create a logical progression in the game.

Credits:

Created by John Jeong

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jeongyej - Windows.zip 29 MB
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jeongyej - MacOS.zip 38 MB