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Starcraft II’s ladder system

August 17, 2010

Blizzard is rolling out some powerful marketing techniques for Starcraft II. Everyone knows the notoriously effective achievements system – this is well-implemented in SCII. But another thing I think is novel for an RTS game is “rested XP.” In WoW, players accrue “rested XP” when they don’t play. This temporarily grants you double XP when you return to play. this serves several functions – it is an incentive for players to return after periods of not playing and encourages daily, regular play (rested XP is capped, so you have to use it to get more).

I was surprised to see Blizzard adapt this concept to Starcraft II. In SCII, players compete on to climb the ladder. But how are players ranked? This is where it gets interesting. Blizzard wanted to implement “rested XP” to ladder rankings – as in, you accrue “bonus points” when you don’t play for periods of time, and when you return to play, you are rewarded with double points for winning matches. But wait – doesn’t this skew ladder rankings? Shouldn’t ladder rankings be based purely on skill instead of on which players grind bonus points on a daily basis? Wouldn’t serious players protest at such a system?

Their solution: Players are placed into leagues based on their matchmaking rating – just like chess it rewards players based on match outcomes and the skill level of their opponents. This matchmaking rating (MMR), however, is kept hidden from players. Instead, players are shown a “ranking” based on “points.” Points are related to match performance in that you gain points for winning and lose points for losing, however, you get “bonus points” from your “bonus pool” that accrue during periods of not playing.

The ranking system that is based on points also displays to you a list of 100 other players in your unique league pool. This gives players a sense of progression as they advance to the “top” of their league pool by winning matches and grinding “bonus points.” However, the 100 players in your pool are chosen seemingly at random from players in your league and when searching for games you are no more likely to play against players in your pool than against anyone else. Also, since ranking is based on points, which are inflated by daily grind-style play to drain your bonus pool, a player could actually be at the “top” of their league pool, but with a low MMR. In Heartborne’s excellent article, he notes that a player could very well be at the “top” of their platinum league pool, but about to be demoted to gold league (due to a falling MMR). This is because ranking and MMR are two different stats. One is skill-based (and hidden) – the other is a combination of skill and utilization of “bonus points.”

In a sense, Blizzard is having their cake and eating it too. Casual players will be “fooled” by the points system and pool “ranking” and be influenced to utilize the “bonus pool” (AKA rested XP), while more hardcore players, with a little research, will fathom that points and rankings are just smoke-and-mirrors, while actual MMR is hidden and your placement in a league and win/loss record is the only indication of skill-level and rating.

Credit goes to Heartborne’s excellent article for “cracking the code” of’s ladder system and I apologize for my overuse of “quotation marks” in this post.


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  1. Excalibur_Z permalink

    Hi Phosphoro,

    I wrote a couple of posts on the Team Liquid forums detailing how the SC2 ladder system is believed to operate, and you can find them here:

    In reference to those threads, I’d like to make a correction here about the Bonus Pool. The Bonus Pool is not analogous to rested XP because it accumulates at the same rate whether you are playing or not. The estimated rate is 1 point per 2 hours. That means that if you expended all your bonus pool and played and won games for 2 hours straight after that, one of your games would show “+7 (You were Slightly Favored) +1 Bonus” The Bonus Pool accrual is more noticeable when you haven’t been playing, but in actuality the rate doesn’t change.

  2. phosphoro permalink

    Thanks for the reply, I’m checking out the articles now.

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