The one thing I've always struggled with is creating a story, it halts every single project I've ever worked on. We must be in the twilight zone because I've actually come up with a plot, from beginning to end (it kinda wrote itself). I may very well be on my way to creating my first proper little game, yay!
So the number one complaint I get so far is the levels are simply too large. What's funny is in testing I deemed levels taking too long and actually shortened them. Figuring I could beat them in 5-6 minutes so players would be able to do so in probably double that. I was apparently very mistaken, only one player has mentioned even reaching the second area. Let alone the first boss.