With Reaper's Due I've been getting the "Chess with Death" event very often, even if I have supernatural events off! How do I turn it off or beat it?
First of all - how do you turn it off?
You don't. If you have Reaper's Due enabled, the event will happen. Turning off supernatural events imposes limits on when it can happen. With supernatural events it can happen to anyone, without - only to Christian rulers or if you have a Christian county (by owner, not county religion) bordering your realm. The chances that you get it are increased if you are unwell, old or the Plague is rampant in your realm.
How does one win the game? (accurate as off 16-feb-2017)
The first option is obvious - straight up attack for an 80% chance to die. In the other 20% you will either lose a limb, be mangled or just wounded. This is the worse option in general.
If you choose to play chess, you will have 3 rounds to accumulate at least 5 points. Great moves net 2 points, good ones - 1 point, neutral doesn't affect the score, bad reduces your score by 1, terrible - by 2 (effectively nuking your character). This is the basic premise, but your actions and traits can influence the game, allowing for higher win chances. Game master and Genius are the most useful traits here, increasing your chances dramatically (Game Master is slightly better, but these two do not stack).
First of all - invite Death in (or pay some money for the nearest inn)!!! This will grant you 1 extra point in the beginning of the game. Secondly - play black. This gives you another point to start with, making this much easier.
The below will assume you've done this, and you only need 3 points to win, from a maximum of 6.
Apart from the 2 usual options (risky or safe), there are a number of traits that allow you to get safe points. These are:
Deceitful, schemer, strategist, quick, shrewd - get 1 point.
Genius, game master - get 2 points.
The normal options are:
Safe - good/neutral/bad for 25/55/20
Risky - great/good/terrible for 20/40/40
This is where various cheating strategies can work. Again, there are a number of traits that get you free points here, as well as the option to concentrate or cheat.
Drunkard, hedonist, seducer, impaler - get 2 free points.
Game master - get 1 free point.
Concentrate - good/neutral at 25/75
Cheat - good/die at 67/33
This is where you have the option to sacrifice a loved one or trust your skill. However!!! A game master still gets better chances than usual if trusting his/her skill.
Sacrifice - great/good/neutral/bad of 15/35/35/15
Skill - good/neutral/bad of 20/50/30
Skill (Game Master) - great/good/neutral/bad of 20/30/30/20
Characters without any special traits, but that are willing to take on the sacrifice stand a decent chance to cheat Death. As stated above, the key point is to be gracious and play black.
The main point to take away is that if you can score 2 free points, you're (almost) guaranteed to win, no need to risk by cheating or sacrificing. If you can score 1, it's kinda dangerous. If you do not have beneficial stats, getting a "Bad" move is the same as getting a "Terrible" move - both end the game. The various chances to win for a character with no traits are below:
Risky play -> cheat:
0.2*(2/3)*0.85 + 0.4*(2/3)*0.5 = 24.6%
Risky play -> Concentrate:
0.2*0.25*0.85 + 0.2*0.75*0.5 + 0.4*0.25*0.5 + 0.4*0.75*0.15 = 21.25%
Safe play -> cheat:
0.25*(2/3)*0.5 + 0.55*(2/3)*0.15 = 13.8%
Safe play -> concentrate:
0.25*(0.25*0.5 + 0.75*0.15) + 0.55*0.25*0.15 = 8%
The top trait combinations are:
Game master + Drunkard = 100% survival (no need to cheat or sacrifice)
Genius + drunk/hedonist/seducer/impaler = 100% (no need to cheat or sacrifice)
Games Master = 85% survival with sacrifice or 80% without
2/3*0.85 = 56.6% if cheating or
0.25*0.85 + 0.75*0.5=58.75% if concentrating
P.S. If you win, Death will leave you a nice present :)