Background
One of the criticisms of the last play test was that, for enemies with certain defence scores, the player only had to spend 2 attribute points to definitely succeed in their attacks against the creatures, removing any tension from the situation. This made me realise that I hadn't actually looked at the dice and attribute points spent to see what the probabilities of success and failure were. How likely is it for an attack to be successful, if an enemy has a defence score of 1 and a player spends 1 attribute point? I would not have had the foggiest idea.
Explanation of the System
A brief explanation of the system I am talking about for those that do not know or have forgotten. When a player wants to use an attack or make a skill check, their character will use one of three attributes: Physique, Intelligence or Vision. The player tries to reach a specified target number by spending attribute points and rolling a die which is added to the number of attribute points spent. The player decides how many attribute points they wish to spend, with the maximum allowed determined by which character the player is playing and which attribute is being used. For example, the Deadeye allows a player to spend up to three attribute points for a Vision check, whereas the Officer only allows a maximum of two. The player then rolls a custom 8-sided die and adds that to the number of attribute points spent. If this result is greater than or equal to the target number than the character has succeeded.
The New Custom Die
I worked out what probabilities would be acceptable and crunched the numbers and came up with following 8-sided custom die:
-2, -2, -1, 0, 1, 1, 2, 3
This has an average of: 0.25
I have constructed tables to show the probability of a character succeeding depending on the target number and the number of attribute points spent.
You may have noticed that if the player spends 3 attribute points to attack an opponent with a defence of 1, then they are guaranteed to hit. To which I say, fine, if they want to spend 3 attribute points on such a weak foe to guarantee a hit then crack on. Spending one fewer attribute point still gives them a 75% chance of hitting, so it is up to them whether they want to spend that extra point to guarantee the hit. I'm hoping that the game will end up rationing the attribute points so much that the player will have to think long and hard about whether that guarantee is worth spending the extra point on.
The default defence score will be 2, with stronger enemies using 3 and weaker ones using 1. If an enemy has a really strong defence then it will be 4.
On average, I think the players should be succeeding about 66% of the time, which if the player is spending 2 or 3 points attacking a defence of 2, is about right. It is vital to get the balance right between not frustrating the players (by making them feel like they cannot progress) and losing the tension (by making the game too easy). Maybe I have pitched this number too high, but the playtests will reveal that and now that I have my spreadsheet and a better understanding of how this points-spend-plus-die-roll-system works it should be easy to tweak in future.
The Weak Die
The die outlined above is the normal die that the player will be using for the majority of the game. However, certain negative conditions will force the player to use a "weak" die. The faces of the "weak" die are as follows:
-2, -2, -2, -1, 0, 1, 1, 2
Average: -0.375
For the weak die, the probabilities of succeeding given a certain points spend is as follows:
The Better Die
There will also be certain abilities that mean a player will use a better die for their rolls. The distribution of the better die is as follows:
-2, -1, 0, 1, 2, 2, 3, 4
Average: 1.125
For this "better" die, the probabilities of succeeding given a certain points spend is as follows:
Conclusion
I have changed the die system to what I feel is a better system. Please let me know if you spot any glaring flaws in this or if you feel that the percentages for the normal die are too high or too low.