My first thought I think is 99% not possible, but is it possible to get rid of the cannot place unit at yada yada location? ( so that it will never appear )

Or

What is mountain side considered? Hillside?
Low terrain
Mid
High

Create them at a separate isolated location that will never be clogged (like a 15x15 regular square of terrain), and then move them to wherever you want??

It is possible to get rid of the error message, but not the root cause of the problem.

You get the error if it can't create a unit at the given location (unwalkable terrain/no space for ground units, no space for air units), however attempting to move a unit to such a location will *not* produce the error message (but nor will the unit be moved).

So to avoid the error message, always spawn your units in a special 'spawning pen' somewhere on the map (that players cannot normally get to), and then move them to where you want them to be. Finally remove any units still left in the spawning pen after the move (they will still be there if the move failed).

Doing all the above, instead of:
1. No unit appearing where you want it
2. A "cannot place unit" error appearing

You will get:
1. No unit appearing where you want it

Unfortunately there is no way around #1, except to ensure there is enough space for the unit, and that you aren't trying to move it to unwalkable terrain.


I'm not sure what your second terrain question is about, so I'll let someone else answer that.

What is mountainside/hillside?
Besides why don't you test it yourself? Just place 3 locations over the marked area one only high air, another mid air, and the third only low air ticked and place an air unit there. Then just detect which location finds the unit.

Good point... However, I do like the idea of pre-placing the unit elsewhere.

Create unit works like this:
The game checks to see if it can place a unit at the center of the location. If the location is too close to unwalkable terrain, or the location itself is smaller than the size of the unit, an error will occur and the unit won't be placed.

If there is room on the terrain for the unit to be placed, it then checks the units in the area. The unit will be placed at the first opening based on half squares, or something like that. See mobile grids for the general order.

If there is no room on a 15x15 square around the center of the location, units will not be placed. I'm not sure of the size here, but suffice to say a 33x33 pixel location will have room for lots more than just one unit.

Moving units doesn't take the unit being moved collision box into account, so moving a stacked unit will always move it on the center of the location.