In D&D 4E, characters and monsters can move up to their speed in any direction, regardless of whether that direction is a rank, file, or diagonal. This makes no sense whatsoever.
A square on a combat grid in D&D 4E is considered to be a five foot by five foot square. So a character with a movement of six can move up to thirty feet along a rank or file. However, corner to corner length of a five foot square is just over seven feet. This means that a character with a movement of six moving completely along a diagonal line on the grid can move a distance of forty-two feet.
That’s twelve extra feet of movement. Or, two and a half squares, along a rank or file.
This bugs me considerably. This is probably the only area in the game that bugs me for its lack of verisimilitude. I could care less about realism in combat, except this thing just rubs me the wrong way. Considering how much they dropped and changed from previous editions of the game, I just don’t understand why D&D designers decided to stay with the square grid for combat, when there are better, more realistic options available.
The first option is a hex map. The drawback to hexmaps is that you often end up with half-hexes if you draw straight lines, because most rooms and corridors are built along ninety degree angles. This causes problems when drawing out combat on your chessex map. Can a character move into a half-hex? Why or why not? It’s really more difficult than its worth.
The second option, that I like a lot more, is simply using a ruler, and good old-fashioned inches. If a character is within a half-inch they’re considered adjacent. This is assuming you’re using circular monster tokens (squares can make things a little more confusing on that front, though not impossible). If this idea gets some traction or requests, I’ll happily come up with some printable templates for powers that use blasts, cones, circles, etc. The only problem with this approach, really, is if you have a rowdy group that tends to knock the combat board around a lot, it’ll be easier for them to cheat when they put the pieces back where they “belong”.