Very clever that you made a puzzle game with randomly generated levels! That must have taken some thinking. I did find that having it be endless took away a sense of progression that I usually enjoy in puzzle games. It just made the levels a little less satisfying to beat for me.
Also, I got the same issue as Turkey, there were walls blocking Lewis' way to the exit one time. The wall I suspect was the problem had one wall to its bottom left and one to its top right, all other adjacent squares were empty, if that helps.
I did think it was a solid entry on the whole though, and enjoyed the early Yogscast vibes!