[schattschneider]

This article doesn't describe it in detail. One scenario imaginable would be that they ran their model trained on non-full moon data for an evaluation on a full moon day. Which means the model would simply apply it's learned "optimal" action policy in a different environment, where the previously learned action policy doesn't lead to good scores anymore.

[laurencei]

So does this mean if they allowed the game to run on "full moon days", it would be expected to eventually get a higher score (if the full moon day allowed that through the actual game mechanism)?

[chongli]

Yes, the full moon day can help you get a higher score due to the bonus luck you get that day. On the other hand, the full moon day makes werewolves (and wererats and werejackals) a lot more dangerous because they'll always be in animal form.

When you try to fight a werecreature in animal form it can summon large numbers of animals of its kind to attack you. This can be extremely deadly for a player who is unaware of this ability. An experienced player knows to attack werecreatures only at range or avoid fighting them altogether. However, encountering the werecreature in its human form is much less dangerous unless it's carrying a powerful weapon.