For a very long time, I have seen creatures such as dragons, rocs, bronze collosi, and forgotten beasts take up the same amount of space as a fluffy wambler (An in certain cases, even killed by one).
This suggestion will attempt to remedy this.
Here is my idea: Make large creatures be composed of several "creature parts", which form the shape of the creature and take up their own tiles.
Essentially, this would make, say, a bronze colossus that is made up of:
head creature
chest creature
waist creature
upper arm creatures
lower arm creatures
upper leg creatures
lower leg creatures.
These different creatures would represent all of the body parts within that area. For example:
the upper arm creature would have the shoulder and upper arm.
The lower arm creature would be the elbow, lower arm, hand, and fingers.
The chest creature would contain the heart
The waist creature would contain intestines, stomach, spleen, kidney, etc.
The head creature would have the brain, ears, mouth, nose, etc.
And so on and so forth for the rest of the body parts.
This suggestion would cause a Bronze Colossus to become 5 tiles tall, 3 tiles wide, and 1 tile thick, instead of being a 1x1x1 box.
This body plan would only apply to megabeasts, titans, forgotten beasts, and certain clowns.
Please let me know what you think, and leave constructive criticisms!