Color Blind Gamers
And now, a Public Service Announcement:
About 8% of males in the US are color blind, the most common type being red-green color blind, followed by the rarer blue-yellow color blind. If you are color blind, it literally means that the colors look the same to you — you see one color instead of two. If you mixed in some red marbles with green marbles, a red-green color blind person could not tell which were which.
Some people are color blind to some degree and don't even know it (how can you be aware of a difference you can't see?) and lots of people who do know are still shy about telling anyone. It's pretty normal to want to hide a disability, even one as mild as color blindness.
What does all this have to do with gaming? It means there is about a 50% chance there is someone with color blindness in your gaming group whether you know it or not.
When you set up the battlemap, and place all those nice markers and say something like “the green ones are the elves, the red ones are the orcs,” someone at the table may just be nodding and maybe squinting a little and trying to figure out which are which. That player who is really bad at those swirling battlemap combats might not be such an awful tactician, he might just have a lot less information to work with than you think.
Take a look at the pieces for many war/board games — it's clear that the industry does not recognize this problem. Lots of games use colored pieces for different players with shades that can be hard to tell apart even if you're not color blind (were my units tan, sandy or brown?)
What can you do to avoid it being a problem at your table?
Classic games like chess and checkers use colors with strong contrast (black and white, red and black) making it easy to tell them apart. A color blind person can still see differences in brightness, even when they can't distinguish colors, so a pale red looks different than a dark green. A tip for industry game designers: take a black and white picture of your pieces and see if you can tell them apart.
You can also use symbols or shapes in place of colors. Use d6 for the orcs and pennies for the elves. Playing cards use symbols that make the colors redundant once you know which are which (spades are always black, hearts are always red). If you are drawing on the battlemap or whiteboard, use different types of lines to represent different features (squiggly lines for water, dashed lines for a spell radius) instead of just relying on color.
Last but not least, you can always just ask people. Not everyone will appreciate being put on the spot, so remember to wear your tact hat.