Tabletop Games and the Odds

I have been thinking for a while about probability in tabletop role-playing games. Mechanics that determine actions influenced by chance make for interesting times, but a few things recently have had me thinking seriously about what the odds are of things happening in games. The first thing that has taken my thoughts in this direction are the influences of the OU module that I took on games (mostly on computer games, but there was a good chunk of time spent on the philosophy of games). The second was playing Apocalypse World.

In Apocalypse World, virtually every action that has a chance element is determined by rolling 2d6. Without any modifier, one needs a 7 to get a "hit" (at least some kind of success), and a 10 or better to get a high hit. There are 11 outcomes (2, 3, ..., 11, 12) for rolling 2d6. The probability of getting a particular outcome is not evenly distributed though - you have to get 1 on both dice to get an outcome of 2, but there are six ways of making your required 7 minimum.

Without modifiers, any chance situation has a 21 in 36 chance of working out (at least somewhat) in the player's favour. More than half, actually, 7 in 12. This makes for quite a balanced sort of game mechanic (I think). But by the end of the campaign my character had a +3 modifier for whenever he tried to do something involving aggression or violence (my character's class was "Gunlugger"). So then from a 4 onwards he was going to get a "hit" - maybe not totally get his whole way on a situation, but he would be successful. What does that mean? Avoid a 2 and a 3 and I'm home free! (well, OK, more or less). Suddenly I have an 11 out of 12 chance of some success. Quite a jump. And the chance of me getting a high hit is more than 50/50.

So OK, enough of all that: this has lead me to thinking that there must be a simple way of qualifying the odds of getting X or more on 2d6. Or Y on 3d8. Or Z on AdN (arbitrary integer A, N (and X, Y, Z)). It is simple enough to draw some tables, noodle some numbers down and do it case-by-case. But my gut says that there is a formula. If this screams "Obviously!" then for now please don't tell me, I want to see if I can get this from working some examples and then generalise. More to follow on this, when I have time to work it out.

Dog Days

I have recently got into tabletop roleplaying games. I have read about the hobby for years and years, but never known how to break into it. Last autumn a friend suggested that I come along to a game that a mutual friend was going to GM and see what I thought.

After three hours of play my thoughts were mostly, "Wow."

We were playing Apocalypse World, a game by D. Vincent Baker, and there was a lot about the game that I really liked (I have written some blog posts about it before, here, here and here; I'm sure I will write some more on this blog as well). Recently our group has shifted games to an alternate present setting that is being run with Cyberpunk 2020 rules, which has been hugely entertaining - the mechanics of play are quite different, the setting is light years away from Apocalypse World, and our party has an unfortunate tendency to get severely injured (although not my character, I am happy to say!).

Over the last few weeks I have been reading through the mechanics and setting for another game by D. Vincent Baker, Dogs in the Vineyard. Again, vastly different to both games I've mentioned so far, but keeping the real streak of relationships and consequences of both games that our group have played recently.

I've never GMed a game before, but with some more re-reading and assimilation of the core of Dogs, I think I'm going to put myself forward to GM a campaign later in the year. The setting just calls out to me: gun-slinging missionaries whose word is law; travelling from town to town to keep the peace, calling the Faithful and casting out demons. Really, what's not to like? There are lots of dice used, but the emphasis with them is the random nature of the dice supporting the storytelling; it's really about a great unfolding collaborative narrative that is stitched together by the GM and the players (rather like the distinctive coats that the game's Dogs wear).

So anyway: I expect that over the coming months I'll be posting up some notes on here, as and when I get some ideas in place - although there won't be spoilers for the players who will be taking part!