At some point in the last week or so I created a character power called, “Block Passage.” The idea I was working with, and the question I was asking was, “should creatures automatically block the passage of other creatures through the space they occupy?” Dungeons & Dragons assumes they generally do, but I wondered why.

Drawing inspiration from Chess, namely the knight, I started wondering if perhaps “blocking” a space by occupying it might be regarded as a special feature. Fourth Edition has some exceptions to the rule in conjurations, which are spell effects that occupy a space but don’t block movement. It was the division that intrigued me.

If an effect could occupy a space and not block movement, then occupying and blocking were different things, right? I came up with some different uses for a “blocking” power as an option for creatures and characters to prevent opponents entering their space. It seemed like a great idea and I couldn’t find any problems.

This afternoon it occurred to me why making “blocking” a voluntary sort of thing would ultimately be more trouble than it’s worth. I like to do new things, so this came as something of a letdown. In addition to the fact that players will likely expect creatures to block spaces, checking whether they do or not is unnecessarily complicated.

And that’s pretty much the reason why it’s better to assume that creatures block spaces. Because if you don’t assume they do, you have to check every one. And sometimes you won’t remember, and sometimes you’ll get lied to or tricked or someone will have to look something up in a book and that wastes time.

It’s simply easier to assume an occupied space is also blocked, and then create powers and abilities based upon that most basic of assumptions. If your character can vault over walls as a means of bypassing them and you’re faced with a wall of air that you can just move through, your vaulting power is still useful most of the time.

So, I don’t see a reason not to continue exploring occupation and impassibility as mechanics, it’s just unlikely that I’ll make any huge changes in the field. *sigh*