[Evil Dave]

I can try...

2d6 is your bread-and-butter die roll for games: throw two six-sided dice and add them. If you do this a lot and keep stats, you'll see that you get a bell-shaped distribution centered at seven, and obviously, the score is limited to two to twelve.

The OE is short for "open ended". It's a bit different: throw two dice as before, but if you get any sixes, roll another die for each one. Keep doing this as long as you keeping rolling sixes. Then add up the all the dice. OK, there's a further twist that for each of the additional dice you throw, you substract one point, so they give 0-5 rather than 1-6.

So, 2d6OE gives stats that are a bit different. The distribution of scores is biased a little towards higher numbers, and there's (in principle) no upper limit. Of course, the odds of getting very large numbers are pretty slim.

Dom2 uses lots of 2d6OE rolls, especially for attacks and defenses. What this means to players is that sometimes odd things happen. Once in a while, a wimp with a knife will hurt a knight, or a crushing blow will be absorbed by light armor -- or a sure-thing attack will just miss, because the defender got an unusually high dodge roll.

As Gandalf said, some people don't like this, because it messes up their finely-honed strategies. I do like it, because lucky shots have been a part of war pretty much since the beginning.