Each orb already does keep track of its own size... Spride.Width, for example, since they are circular.

Well, a free scrub like me can't use families. You *could* probably go:

On Collide Planet (sun) -> Planet (sun)

--System -> Pick Nth Instance Planet (sun) 1 | Planet -> Destroy

--System -> Pick Nth Instance Planet (sun) 0 | Planet -> Destroy

What's wrong with having that condition?

Of course, the simpler solution is this: Make both types of walls Solid, disable "bounce off of solid objects" on the bullet, and add a condition:

Bullet -> On Collision with SolidWall | Bullet -> Bounce Bullet off SolidWall.

Here's an example I put together. The controls aren't a perfect match for 8-directional, but with a little tweaking you might get movement like what you want.

If you want to go a a roundabout way of doing this, you can double up on the Physics and the Solid behavior; shoot-through walls will just have physics + immovable + no rotate, but regular walls will have that and Solid together. You won't be able to just use 8-direction for your player, though; to get it to react properly to physics objects, it will need to move by its physics behaviors.

I think this is might be something best solved by using Families. (See the manual for how they work.)

That would let you deal with all "boxes" the same way for some effects. Unfortunately, families are not available to free users (like myself.)

You don't want a "Tiled Background"- you might want a Tilemap, instead.

Can you show what you mean by "that weird tiling effect"? Preferably with an attached image?

SetColor doesn't seem to work for me at all. I guess my preview doesn't webGL?

scirra.com/tutorials/237/ho ... -web-fonts

Event: System -> Compare Two Values Distance(p1.X,p1.Y,p2.X,p2.Y) <= WindowWidth