This was a decent challenge! I wonder how many achievements there are total?
Well played! There are 6 achievements in total. One of them is the "Hidden Neco-arc", I believe almost nobody got it.
theres 2 secret places, top of the isolated building, high jump and neco arc, cant find the last one :(
I think you have all of them if you found the missing Neco-Arc!
Achievement list (as of now):