-10 for killing the last remaining unit of any power, including POWs.
Conspiracy with the enemy (e.g. Germany and USSR standing by their nonaggression pact despite a phony declaration of war):
Germany gets -3 for every turn after round 4 that Germany has not attacked any Soviet controlled territory or naval unit and has not placed any warships in z125.
USSR gets -3 for every turn after round 4 that USSR has not attacked any German controlled territory or naval unit and has not placed any warships in any German convoy raid zones.
Anytime you capture an enemy’s capitol and seize their national treasure (gold, money, works of art, secret files, execution of intellectuals, etc.) you incur -5 war crimes points.