Prevent actors from entering regions

I was wondering if there was a way of preventing actors from entering regions. I've tried setting things up with tile collisions, and made sure that the test sprite for my project was set to collide with them, but said sprite just walked through them.

have you tried setting that if character in inside a region to increase/decrease their _y value until they're out?

I tried that, but the behavior I attempted to do that with prevented the game from running.

Couldn't you use terrain instead? (I don't know, it's not the right solution if other actors have to go inside the areas you don't want this specific actor to enter.)

The thing is, in this little test scene, the actor isn't supposed to enter the black(ish) part of the scene. Also, I tried finding behavior blocks for terrain, but couldn't find any that could help me replicate the behavior I tried in the first place.

Sidenote: Still can't believe that tile collisions don't work properly in top-down/isometric games.

Terrain is considered as tiles. You don't need a behavior. The actor will collide with it as if it was some tiles.
As I said, the only problem is if some other actors have to be able to enter it, then it would be more complicated.

I would describe the "sandy" isometric tiles by 4 lines.

x,y -where I will be in next frame based on my speed x,y speed (custom attribute, not stencyl block)

If (x,y inside the sandy region):
     move actor to x,y
else:
     do nothing/stop

Can't you use terrain (as mentioned) and then assign groups to your terrain to determine which actors (players/etc) collide or don't collide with the terrain?

use something like T4u method If you use collision, this means the character head, for example, won't be able to touch the sky.

I would recommend against having concave terrain shapes, btw. Might be true for regions also.

@t4u: Thanks for the help. BTW, is that a scene behavior or an actor behavior?

Actor behavior

Just started to establish the base of that behavior t4u suggested. What's really killing me is finding  blocks for things like  the following:

for the moving half:
if <x_position+vx, y_position+vy inside the sand square>
x_positon+=vx
y_position+=vy

for the region creating half:
pretty much the whole apex thing, since there doesn't seem to be a block that covers that sort of thing. And the Stencylpedia, from what I've checked, doesn't have any info on it either.