Now I am and recently I developed a cooperative game, Narabi.
Currently there are two rating systems in BoardGameArena co-op games:
1. Compare to an artificial rating value against the game according to the difficulty chosen
- Forbidden Island, Hanabi, Pandemic, Solar Storm, Tranquility, Yokai
BGA computes the average of all players in the game, then compares it against a set value according to the difficulty.
This seems reasonable since the gain and loss changes and this can reflect player skills more precisely, in paper.
However, actually it is not. Players may abandon games or avoid beginners to prevent rating loss.
This problem has led many forum threads to flame wars and is still ongoing.
2. Award fixed amount regardless of the difficulty setting and never decrease rating
- Bandido, Similo, The Crews
For simple games with low variance in difficulty, this is not bad. No reason to abandon losing games!
But this cannot reward harder game settings properly, and sometimes this might cause players to end the game faster.
Also, if the increase were too small the game cannot distinguish beginners and experienced players by table setting easily.
Thus, I'll take a different approach this time:
3. Award fixed amount based on the game result and add bonus rating for the game difficulty (also, rating never decreases)
Narabi's score is based on the turns spent to complete the game. The faster players win the game, the better the score is.
However, adding the score itself cannot reflect the game difficulty.
Thus, I'll add the score as base points, then will add bonus points when players win with more players and/or in Advanced mode.
The base increase alone will be enough to distinguish player skills.
With +1~24 rating players can reach Average rank after some victories, but not too many (and achieving higher ranks also can be a motivator).
And bonus points will reward players who faced harder challenges. Besides, no reason to abandon games for rating, again.
I want to hear some opinions or advices on this from BGA players before hitting beta. Thanks in advance!