As I play more campaigns in the level editor, I'm getting better at the game. I have way better reflexes with enemies running at me, I can be more efficient when shooting guns, and I can pull off better combos.
The campaigns I have played so far are the Cold War Trilogy, Heather, Berlin Blitz, and The Rooster Files. The one I am playing now is The Rooster Files, which has Jacket as the playable character. I am on the 4th level out of 9, and it's really good. I also played a lot of single levels, which are really fun and have cut scenes and such in them as well.