I've been reading somewhere (though I cannot find anymore the article) that some MMO games "cheat" when it comes to use "random chance", basically those games make sure that random skills do not get activated too often or to rarely by tweaking the real outcome chance according to how many times the skill failed to activate.
This is to prevent players frustration.

?I would be glad to find again that article, actually I tried to do the same, but since I'm rusty in statistics I failed to do that.

(well in reality it is irrelevant that the game is server-based). I just want to know how to tweak the frequency of success without altering the chance (so if you know that without citing an article you are wellcome :) ).

A pool of numbers is not a good solution. I should use a different pool for each different enemy and skill, and to tweak the % in a really fine way I should use a really big pool (10.000 numbers di per se is not a problem, but 10.000*enemies*skills it is).


?The entropy counter seems very interesting concept, I will check now it it alters also the chance and not only the frequency (actually I tried something similiar and don't worked very well). thanks :) I already played PathOFExile, very nice game.

?The way the etropy counter works generates a fixed sequence, I may tweak it a bit but actually it is not good (to me, in my opinion XD). In example assume that chance of hitting is 50.

?the counter is initialized to 64

?First shot: 64+50 => hit

Counter : 14

Second shot: 14+50 => miss

Counter : 64

Thirdshot: 64+40 => hit

Counter: 14

?In this case the sequence will Always be 1 hit, 1 miss,

?And i fear that changing:
?This:

float hittingChance = CalculateHittingChance();
entropy += hittingChance;

if(hittingChance > 100.0f)
{
    Hit();
    hittingChance -= 100.0f;
}
else
    Miss();

To this one:

float hittingChance = CalculateHittingChance()* Random(0.5f,1.5f);
entropy += hittingChance;

if(hittingChance > 100.0f)
{
    Hit();
    hittingChance -= 100.0f;
}
else
    Miss();

Will alter the final chance.

Thanks I needed something half-way between those 2.

?Actually giving some randomization to the factor that gets added to entropy seems to do the job and get the best of both worlds.. Still struggling to tweak that value but I'm more close to the solution :).

Note that it's not really 'cheating', per se, to use one of these techniques. As long as the actual percentages are preserved, it's still accurate.

One issue is that it's impossible to do both - given that you never know how many future tests there are going to be, you can never guarantee that whatever tweak you make to the current test isn't going to be the final one, and thus over- or under- state the true probability. For instance, in the Path of Exile entropy system (bad name, incidentally), there is a 0% chance that you can be hit 2 times in the first two attacks by someone with a 40% chance to hit, when a more correct value would be 16%. This matters if they only ever manage to have two attacks! These values converge to the right ones, given enough tests (c.f. the law of large numbers) but it will always skew low.