Sorry you had trouble with it. :/ I got a suggestion earlier that easing into the difficulty would help, and I definitely think that would solve the problem. Also, I did try a parallax effect, but I'd never done it before so I didn't think it looked great. Thanks for the feedback, though!
EDIT: I'm starting to realize I'm not great at judging difficulty... I didn't do a ton of playtesting with other people because every time I played it I thought it was too easy. Guess it's more important than I thought to have others test the game!