I think there are a couple of ways to do this. If you can, this might just be a participation grade as we are still in the first Unit and students are getting comfortable - plus the nature of this project is "always in Beta" which it can be improved upon. It seems like all of them did it, so maybe the scale is from 65-100, and there are 9 categories that students had to complete. I sometimes (with journals) give either a 2, 1, or 0. Zero if not done, 1 if done sloppy with no thought and 2 done with thought. This leaves a lot of room to judge students individually on what they are capable of.
For this project I think I only gave a couple B's because they were sloppy, but as students were still making sense of Input/Output/Storage/Processing and trying to come up with something original, some students were impossible to create but I could tell they took a lot of time to do it vs other students that (in the last minute) tried to create a Facebook for the school.
I hope that makes sense, I would - if possible - avoid giving grades on the project but focus on the effort, taking into account prior knowledge of the student to see if they put in there best effort.
Let me know if you have any other questions - or how you ended up grading them!