Dice ex Machina (long)

When making a dice system, you have to consider many things:

1- How many parameters influence the dice. If you roll 1d20 > target number, you have 1 parameter which is determined by the TN. In White wolf system ( ex vampire ) the dice system has 2 parameters : The difficulty of each roll, and the number of success. A 3 parameter dice game, could be like vampire with the option to use D8, D10 and D12 in some situation.

2-The second important thing is the number range on the dice. More numbers on the dices give you more precision. In some games, it can be important. For example, I am currently using a roll X D6 vs TN from 1 to 6. This mean that I am limited to 6 different TN. So it will be hard to make units that has different TN. If I used D10, there I have a wider range of TN and I can create more variety.

3-Third, you can make alteration on the roll. For example, if you are totalising 3D6, you could say in some situation, reroll the lowest/highest dice because it is a enchanted/cursed weapon. Or you could say, roll 5 dice and keep the best/worst 3 dices. The dice alteration can be considered as an additional parameter itself. So you could use my 3 parameter dice system above, add some rerolls and you get 4 parameter dice system.

4-The number of dices that will be rolled is also important for the game play. If you need to roll 10 dices each time, it could be anoying. I even have seen an RPG where you could roll more than 20 dices. This is mostly determined by how you want your game to look like. Like dice number range, rolling more dices gives you a greater range of variations.

5-Finally, you could change the interpretation of the dice. For example, if you roll X D12 <=4, then you could use for example the law of the average. In this case, 1 D12 has 1/3 chance to hit, so theorically, 3 dice will surely make 1 hit. So if you roll 8 dices, then you use 2 groups of 3 dices to make 2 automatic hits and roll the 2 last dices.

As you can see there is many possibilities, you just have to evaluate each element. The most important thing is to determine how many variables will influence the dice roll.

It would help to know what kind of result profile you are after:

Do you want a little randomness to add a little spice or do you want true chaos?

Do you want different levels of success or just succeed/fail?

Do you want an equal chance of all results in a spectrum or do you want a bell curve of results with avaerage numbers being returned more often than extremely high or low numbers?

Justin

By the way, I have made an error for vampire, it is a 3 parameter system:

1-Difficulty level for each die
2-Number of success needed
3-Number of dices rolled

Which mean right now, the most complex dice system I could make is a 5 parameter system by adding :

4-Roll different dice (d8, d10, d12 )
5-Roll modifier ( reroll )

Ha ha ha! ... can anybody do better? (*_*) (god mode face)

like jwalduck said, you have to consider also the probability variation of the dice roll. Rolling 3d4 is diffrent than 2d6 which is different from rolling 1d12.

like hedge-o-matic said, using color and symbol can sometime make the unserstanding easier especially if each sybol has a different distribution on the die. In hero quest, there is 3 skull, 2 white shield and 1 black shield on the combat dices. I also used this kind of dices in the game I am currently making to dertermine if the player is alerted, surprised or hidden.

It is probably possible to evaluate the probabilities of the vampire system. I am not sure if they made it for vampire, I know in an RPG, I think it is Legend of the 5 ring, there is a table which indicates the prob of each roll and keeping combination against the TN.

There are some situations where using a 3 parameter system can be useful. For example, In my game's combat, I need to determine if the weapon hit and how much damage it does.

So thorically I need 2 rolls and 2 variables per roll to influence the roll from the attacker and defender point of view. Since I did not want to make 2 rolls for each battle, I fusioned everything in 1 roll with a 3 parameter system:

Weapon Strength ( NB dice)
Defense ( Target number)
Armor ( Nb sucess required)

In this roll, the weapon strength will represent the to hit potential and the damage potential.

So I guess we can make some sort of deduction that more parameter in each roll can reduce the number of rolls, while less parameters per roll can increase the number of rolls.