The game needs a wall that let pass liquids and gases, and gases only. Only thing needed!.

I'd love to see an element of some sort that will transmit temperature, but not pressure/air currents. Perhaps a wall, since those already block pressure?

I think that there also should be a wall that allows photons and neutron to permeate, i dunno what class/state they they should be described as, maybe 'subatomics' or something that relates to the obscure seemingly mass free particles.

ps: has anyone noticed that we're talking about new walls, on an elements post? :)

We basically need elements which will do the functions of all the walls

It would be great to add a reverse e-wall (uncharged - allows particles) and something like check valve but IMO that will be harder to implement maybe by adding "baggy" wall - solid element which could be moved by air traffic.

I think that there should be a custom element creator. It would be really simple to make. And Simon would not have to program all of the elements himself, just add functionality.