I may have found a bug or maybe the diamond is that huge?  I got to a part where it said I left my keys in one of the dugouts and there was this black bar in my way, but it immediately disappeared, so I went left and it had a 90 degree angle so my character was facing left and I turned down I followed it around and when I got to the bottom right corner, I went down and right.  I was holding down and right for about 2-3 minutes I think and I never hit a wall.  I started going other directions, but there is no texture on the green for the field so I couldn't tell if I was really moving anywhere.  After several more minutes I gave up.  I had 73 or so balls before I ran into the problem. 

Fun, but it moved kind of slowly. Maybe you could make the map smaller or the player move faster? I'm not sure if I reached the end or not, it said that I perished. Nice artstyle and fun game!