The rough chances

Recently, the tinkerage has been working on a rules-lite system inspired by XD20 and Fighting Fantasy, and developing elements from And Play. The result has been a core concept (you could hardly call it even a mechanic) that could apply to any of these systems, or even to a rules ultra-light game like Sword and Backpack.

Now Sword and Backpack (S&B) is inspiring, but it's barely a system, more like the description of what would happen in play: you describe situations, propose actions, roll dice to decide. But the thought occurs that if you could table just the rough chances of success and failure, and use them consistently, you would have the basis of an RPG. Although most games use tables and extensive modifiers, what we are usually looking for are probabilities that 'feel right' and provide a satisfying balance of success and failure that's true to the circumstances.

So here's the rough chances table:

Chances	Roll	Consequences
Very Low	17+	Exceptional (Critical Hit)
Low	14+	Enhanced
Close	11+	Medium
High	7+	Light
Very High	4+	Slight
Exceptionally High	1+	Negligible (scratch)

Using the rough chances table:

• In free-form roleplaying, like And Play or S&B, you weight up the options, pick a chance, and there on the row is your roll for success (d20, of course). Add a few points to make things harder, or deduct a few to make things easier.
• In XD20, where the lower a STAT the better, the table tells you roughly what the chances are by looking at the Roll column. So if a character has a STAT of 8, chances are good. Want to make the chances better or worse? Select another row and estimate the STAT or modifier from there (so if your STAT 8 character fights a STAT 9 orc, it seems the chances are close; go for a roll of 11 or 12).
• And, if you roll for effect (higher being better) then use the Consequences column. You can even use this to judge damage.

You can also convert this table for different dice (such as 2d6 for Fighting Fantasy).

The new system, based on the rough chances table, is coming soon... -ish. Still tinkering with it.