Here's the final outcome. They still glitch-teleport when crowded.

dl.dropbox.com/u/98441819/Construct/Zombieland/zombieland.capx

If you know how to fix this please tell me.

Okay nvm. I fixed it all now, Thanks for all the help!

That worked, but apparently they did overlap again. I dont know why this happens. I only have 2 sprites, one player one enemy. There are two instances of enemy and one player on my layout. player has 8direction behavior while enemy has only solid behavior. But they still overlap.

Then, I tried putting 8behavior on the enemy. Amazingly, they worked. I can control my player using WASD and the monster follows me and they dont overlap. Only problem now is how to make the arrow keys null when pressed so they wont move. Here's a sample capx.

dl.dropbox.com/u/98441819/Construct/Zombieland/sample.capx

I dont think there is an edit button here so i just made another comment.

After a bit of testing:

two instances of the same sprite (with solid behavior only) each controlled by different keys:

solid does work between two instances. I use bullet behavior for my monsters so they always chase the player. Any ideas how I can mimic this behavior without using bullet behavior?

Haven't done this myself but if bullet behavior nullifies solid behaviour, you might want to consider a standard movement method and mimic the bullet behaviour in your events. If you just want them to go towards a straight line you can use linear algebra to set their positions.

Bullet behavior seems to work together with solid only if between two different objects. They dont work between instances of the same object.

Here is my capx, and the methods done by Yann to help me out. Got some problems though. I commented it inside. dl.dropbox.com/u/98441819/Construct/Zombieland/zombieland.capx

The Bullet behavior. What would you do if you're making a top down game?

Sorry man. Wont do again.

Anyone please?

Well they dont apparently. You can try it yourself. The player, treats the NPC as a solid object, because they are two different objects. But the NPC passes through another NPC. (they are instances of the same object)

Solid behavior works alright between different objects. But what about between instances of the same object? Is there a way to do this? I have spent months in figuring out a way. The bounce off objects option in the bullet behavior doesn't look good. They look glitchy in my opinion. Help please? I don't think capx files are needed here.

Okay here it is. Sorry it's my first time.https://dl.dropbox.com/u/98441819/Construct/test%20capx/collision.capx

Help please? Just imagine a player who is blocked by an immovable wall sprite with a solid behavior. Only difference is that the player is the monster and the wall is another monster and both are moving.