I am not completely happy with the wall kits yet. They add great possibilities for the player and allow us to build very hard missions (like Acid Gold Mine) which would be almost impossible to play otherwise.

But in many missions, they cannot be made available because they are so easy to use they would make the mission way too easy.

My suggestion for a change would that wall kits can only be placed if solid material is nearby. I can see several variations of realizing this:
* Placement is only possible if the newly constructed wall directly touches solid material (the preview could be painted red or green just like construction previews)
* Placement is only possible if solid material is within a small range (e.g. five pixels) - would simplify constructions of long bridges a bit and allow you to leave drain holes for water
* Placement is only possible if solid material is within a small range (e.g. five pixels), but it then always snaps to the nearest solid pixel

Missions like Deep Sea Mining would become a bit harder, since you cannot just dive around with a wall kit and a pipe end and always construct breathing holes wherever you are. On the other hand, it's still usually pretty easy to find an island in diving range and attach a wall to that.

What do you think about this change? Does it make sense to make the game harder if people already have some trouble playing the existing missions?