2D shooter tutorial

I think that your modifications are headed in the right direction! Two quick things:

1. When adding new levels, make sure to differentiate them enough so that they have some new element from the other ones.
2. In terms of enemies, I would suggest seeing if you can change what they look like, add new abilities, or change how they interact with the player - these changes should be significant and allow you to practice/learn skills.

I'm looking forward to seeing your final product!