Shapes can be more than simple walls that keep bots out of their insides. Now that we have the infrastructure for bots to see shapes and find out things about them (via refvars) we can use the shape paradym to add environmental complexity. For example, we can have shapes that do the following things:
Hill shapes. The repulsion force is small at the edges, but becomes progressivly stronger towards the center.
Pit shapes. The repulsion force works in reverse of hill shapes.
Nrg sources. Bots on the shape get free nrg. Could scale this as a function of distance from shape center.
Cost Free Zones / Cost multiplier zones. Bots on the shape expereince no costs or dramatically increased costs.
Shapes where ties don't work.
Shapes where shots don't work.
Shapes where nrg shots are everlasting.
Shapes where eyes or poison or venom or viruses don't work.
The possibilities are endless.
Of course, shapes can reside on top of other shapes, so one can imagine combining these things - a hill with a smaller nrg source on the top, high cost shapes in which where nrg shots last forever. The nrg shot remains of corpses bouncing around inside may justify venturing into the higher cost zone and so on.
I'm thinking the first one I will do is the shape "pit of death". Think of it as a hole in the field into which bots can fall to their death. Bots die instantly if they cross the shape edge. .refkills will get updated, allowing bots to detect these pit of death shapes and avoid them.