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#1




Help Calculating Odds for an Alternative Combat System
Working on my own game... even have a Kickstarter.com thing inprogress for it, but not posting a link to that here until I go public with it, and pay the site supporter here .
Since I have attack and defense values for the pieces like heroscape does... I was going to just use what works and use the same multi dice combat system with blue symbols blocking red symbols. However I am trying to go cheap, and knock it down to only using 2 dice, isntead of having to include 1012 or more with the game set. So... after many concepts, I am currently debugging a system that uses a D20 for attack, and a D12 for defense. This obviously will not have the exact same results as the heroscape/heroquest system, but it is close enough for my game, and except for a few issues, I actually like it better. I know a lot of you here like to solve odds problems, I dont lol... I think I have done it right, but If someone could spend their time checking my results... thank you. The system works as follows: I have this explained better in the rule book, but I am going to try to shorten it. Figures/units will have a varying attack or defense value, usually from 1 to 12 in either. When attacking the attacker rolls a D20 and adds his attack value to the roll, and the defender rolls a D12 and adds their defense to their roll. So: ATTACK + D20 VS DEFEND + D12 If the defense is equal too or greater, the attack fails, and is over. If the attack is greater, then damage is done... for the sake of keeping it simple I will just say 1 damage, there are other rules to increase damage though. While this makes it hard to use this system in heroscape, it makes the odds calculation much easier, since you only have to find one hit, not varying amounts. Anyway this is what I came up with for the odds. A = % chance attacker wins D = % chance defender wins The first column shows the difference between the attack and defense... So an attack of 5 and a defense of 12 is going to be D + 7 since D has 7 advantage over the attacker. Since the other 5 on each side, would just be canceled out. You do not have to calculate all this in the game, just to get the odds... (assuming I did it right!) Code:
D + 19 A 0% D 100% D + 18 A 00.42% D 99.58% D + 17 A 01.25% D 98.75% D + 16 A 02.50% D 97.50% D + 15 A 04.17% D 95.83% D + 14 A 06.25% D 93.75% D + 13 A 08.75% D 91.25% D + 12 A 11.67% D 88.33% D + 11 A 15.00% D 18.00% D + 10 A 18.75% D 81.25% D + 9 A 22.92% D 72.08% D + 8 A 27.50% D 72.50% D + 7 A 32.50% D 67.50% D + 6 A 37.50% D 62.50% D + 5 A 42.50% D 57.50% D + 4 A 47.50% D 52.50% D + 3 A 52.50% D 47.50% D + 2 A 57.50% D 42.50% D + 1 A 62.50% D 37.50% A = D A 67.50% D 32.50% A + 1 A 72.50% D 27.50% A + 2 A 77.08% D 22.92% A + 3 A 81.25% D 18.75% A + 4 A 85.00% D 15.00% A + 5 A 88.33% D 11.67% A + 6 A 91.25% D 08.75% A + 7 A 93.75% D 06.25% A + 8 A 95.83% D 04.17% A + 9 A 97.50% D 02.50% A + 10 A 98.75% D 01.25% A + 11 A 99.58% D 00.42% A + 12 A 100% D 0% Since it is hard to search games by combat style, I DID NOT look into other games using this... so it is very likely some do. The issues I spoke of: The 100/0% chance, if you over power you will kill 100% or be unkillable... I dont think this will happen with out limited use special abilities though. I need to use additional rules for the damage... this may actually work with my game though, I have it setup so BEFORE the attack you have to sort of "invest or gamble" on your results, to do more damage, or it is lost if you fail. Thank You for any help, input, comments etc... Last edited by Draconious; April 29th, 2011 at 02:41 PM. 
#2




Re: Help Calculating Odds for an Alternative Combat System
I'm not entirely certain I understand, but assuming that Attack and Defense are equal, the defender automatically loses 40% of the time (whenever a 13+ is rolled on the d20). Again, all things being equal, the other 60% will split close to 50/50 (with the ties going to the defender). That means that your system will produce an almost 70% casualty rate when attack=defense. By comparison with Heroscape, 1Atk v. 1 Def produces a casualty roughly 33% of the time.
~Aldin, who thinks it could also be frustrating for the defender to know that they don't even need to bother to roll 40% of the time He either fears his fate too much or his desserts are small That dares not put it to the touch to gain or lose it all ~James Graham 
#3




Re: Help Calculating Odds for an Alternative Combat System
I guess I should point out, that the equivelent to wounds in my game, can be replaced/healed a lot easier than they can be in heroscape. I wanted a bit more advantage on the attack side because of this. This is why I accepted the A 67.50% D32.50% split when the attacker and defender are equal. Instead of the A 50% D 33% in heroscape.
Also, only one wound per attack will be the norm... unless some moderate risk is taken on the attackers part. (The other rules) And I guess I should also point out that the RANGE value is not seperate in my game, the Attack value also represents range. And each space of disance beteween the attacker and target, reduces the attack by 1. So if you have 7 attack, and attack 6 spaces away, you lose 5 (you dont count the adjacent space), and only have 2 Attack... I do not expect anyone to actually use this system in heroscape, but it could potentially be taken a different route if anyone wanted to try it. I am mostly curious if I did the odds in the first post properly? Last edited by Draconious; April 29th, 2011 at 02:48 PM. 
#4




Re: Help Calculating Odds for an Alternative Combat System
Quote:
~Aldin, bowing out He either fears his fate too much or his desserts are small That dares not put it to the touch to gain or lose it all ~James Graham 
#5




Re: Help Calculating Odds for an Alternative Combat System
I don't know how to do it with math, but the probability is basically just figuring out how many of each possible combination of die rolls would be a success out of the total possible combinations. Your total combinations will be 240 (20 x 12). The easiest way to do it without figuring out the actual mathematic "short cut" would be to go into a spreadsheet and start with 120, twelve times each in the first column, then 112 repeating for each 1, 2, etc in the second column. The third column could then have a 1 for each instance where the attack wins, the fourth column has a 1 for each instance where the defense wins. Then sum the third and fourth columns and divide by 240. I'm sure there are easier ways to do it, but I don't know them.
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#6




Re: Help Calculating Odds for an Alternative Combat System
Well that is pretty much what I did, so hopefully I did it right...
thnx 
#7




Re: Help Calculating Odds for an Alternative Combat System
I played with a spreadsheet a little and it looks like I'm getting the same numbers. I didn't check every iteration of attack and defense values, but I did about 8 or so with the same results. For reference, I did it with the 120 and 112 being sums of the die roll plus a bonus. Then the 1 for a success is put in with a IF function. That let me check numbers for a bunch of different attack and defense bonuses quickly.
That was kind of enjoyable, and it didn't take that much time. It kind of makes me want to figure out probabilities for the different attack/defense scenarios in Space Hulk. Follow the adventures of Agent Minivann
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#8




Re: Help Calculating Odds for an Alternative Combat System
Thank You, it is nice to be more confident in the numbers .
Now I just need to figure out if this will work propperly in my game or not... Aldin, I wasnt trying to stop your help... I just noticed a lot of my original post sounded like I was trying to convert the heroscape combat system, and I was just trying to convert mine after trying the scape system. I havea habit of typing a bunch of things that go off on tangents, like now, and I was just trying to save a the thread from going too far off topic with a bunch of "this wont work in heroscape" posts. I am still trying to figure out what you meant by the odds, if there is something that will make this system really suck for my game then I guess I need to figure that out... Thanks. 

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