there is no bug on level 13, because your'e supposed to connect the white circles to the green squares below them.
You've got a huge bug on level 13, where you can't connect the structures. The people either appear in the upper left corner, or don't at all. The level is uncompletable.
Explanations were a little confusing and members failing due to buckling should occur more often imho. Overall addicting and fun especially as a engineer. Still trying to get 3 stars on a couple levels.
Quite good game, both the concept and the implementation. The only annoying thing is that it sometimes is hard to get the part to "snap" to the fixing points.
Simple, easy game. Not very original