Hi, I've been doing some research and I think that the easiest way to save a world is by pickling. Pybox2d already supports it so it is pretty straightforward. I think this should be implemented at the level of Elements and not directly on the activity. Should I do it in the modified elements we have inside the activity or should we try to unify the different elements versions? I personally will prefer to unify the versions to get more benefit from the work. We should take into account that after I finish with "world saving" I will work on some new features for the activity that will require adding features to elements. There are other alternatives for world saving. An objection to pickling is that is not human readable and we won't be able to edit scenes with a text editor but I think that it's better if we add and polish editing features directly in the activity. The odds that the end user will try to edit a scene with a text editor are minimal. Greetings, Asaf