We are finally in a position to announce the arrival of a long sought-after feature - RetroPoints!

This figure is a value which represents the relative difficulty and rarity of an achievement, depending on how many people have achieved it within a game.

See an example on any game page: Sonic the Hedgehog (Mega Drive) - The small white value is the RetroRatio value.

The RetroRatio takes the regular point value into account, and produces a new value which is given by:

p = points
a = achievers
t = total users who have played the game
r = 0.6
RP = p*r + p*(a/t)*(1-r)
RP = p * r + ( p * ( t / a ) * ( 1 - r ) )

This means that the regular point value will always be a base for the RP value (assuming that at least one person has earned the achievement), and it will always be greater than this value.

See the 'hardest' (or 'rarest') achievements at this link: https://retroachievements.org/achievementList.php?s=14&p=2 and hardest games here: https://retroachievements.org/gameSearch.php?p=0

Please let us know what you think, if it needs adjusting etc. We have regular recalculations set up now ready which are recalculating every achievement and user's total point and RetroPoint value every 24 hours.

Thanks!

Edit: sorry, that's what I get for rushing lol

RP = p*r + p*(a/t)*(1-r)

This means that the regular point value will always be a base for the RP value (assuming that at least one person has earned the achievement), and it will always be greater than this value.

I am assuming RP in this equation is the RetroPoints value that appears in parentheses for each achievement? Based on that equation, the value of RP will equal the base when the number of achievers is equal to the total users who have played the game, but this value is less than the base value for any other case because a/t <= 1.

For example, substituting values for the Immortal (50) achievement which is showing a RP value of 990:

p = 50
a = 1
t = 48
r = 0.4
RP = 50*0.4 + 50*(1/48)*(1-0.4) = 20.625

Ooohhh uh maybe t/a instead?

That gives 1460 which is really far off as well.

$ratioFactor = 0.4;
$newTrueRatio = ( $achPoints * ( 1.0-$ratioFactor) ) + ( $achPoints * ( ( $numEarners / $numAchieved ) * $ratioFactor ) );

Ah sorry -

RP = p * 0.6 + ( p * ( t / a ) * 0.4 )

I think ratio should have been 0.6, sorry

Ok, everything adds up now. Thanks for clarification!

No probs, sorry it took so long to get right :P that's what I get for rushing :P

About achievements that haven't been earned by anyone yet:
Can the value be set to pretend one person got it? Rather than zero or infinite. Because if someone were to get it, that would be what it's worth.

OK so force every t to be at least 1? This could have a very interesting impact on the values, but let's see what effect it has. I'll make the change now, by this time tomorrow it will have taken effect. Cheers brian

Edit: ah, its a little more complicated than that - I'll get back to you asap, sorry brian

The retropoints should be exclusive on hardcore mode. Don't you think?

^ I agree with the above comment. Pretty much all the "super hard" achievements can be obtained with save state abuse.

^ I second this

^ I third this

^ I fourth this

So THIS is what the white numbers mean! Well then, time to see how I stack up in this alternate system...