Yeah, it tooks us about 2 months of playing around with level design (while working on coding the game) to figure out how to make challenging levels that couldn't be easily circumvented. Of course, we didn't have enough time to make all of them, but whatever. Experience is good.
By the way, everything, except for how it handles animations, was custom coded, by our group, and I did the majority of the coding. The code is the real product of the project, not the gameplay. If we would have had more time (2 more months), gameplay would have been MUCH better, but oh well.