Here's a fast tutorial for creating custom collision boxes: First of all, map assets from XCOM1 must be rescaled, they are 100 times bigger than the XCOM2 ones, so when importing resize them down to 1%.Blender problem, use 3dmax instead. Collision boxes must be convex, made from a set of convex brushes. 1)Create a copy of the object and move it away from all the others http://i.imgur.com/doGBNfk.jpg 2)Select the Brush tool and set it to the desired size, for the first step let it be a box with X= 96*2 = 192 Y= 96 (regular xcom tile) Z= 64 (half-cover) http://i.imgur.com/JjGDmur.jpg Align it with the model and click "ADD", do the same with the other side and the center part. http://i.imgur.com/TZgcjU3.jpg http://i.imgur.com/DPb9v78.jpg http://i.imgur.com/uFM5fwO.jpg For the slopes, align a 96x192x64 box and select Geometry Mode http://i.imgur.com/c9RqFxY.jpg Select the destination vertex http://i.imgur.com/C0Y6aFJ.jpg then the one that has to collapse http://i.imgur.com/ZuoJs7x.jpg then hit WELD http://i.imgur.com/2x46nL8.jpg