Gas Attack: Once per turn starting on Turn 3, countries can promote 1 extra attacking infantry in one territory only to the “Infantry with Supporting Artillery” dice box for each artillery in the territory.
Morale Defeat: Optional morale victory conditions can be: Morale starts at 0 and ranges from 10 to -20 on each side. The Russian Revolution rules are not used with Morale Defeat in effect. A country gains morale by: Capturing a territory(+3 morale), liberating a territory(+2 morale), liberating an allied territory(+1 morale), destroying an enemy battleship(+1 morale), capturing a capital(+5 morale), liberating a capital(+3 morale), or ally capturing a capital(+2 morale). A country loses morale by: Losing a territory(-2 morale), losing their capital(-7 morale), losing a battleship(-1 morale), ally losing a capital(-3 morale), every ten casualties suffered(-1 morale), or not mounting an attack in a turn(-1 morale). In addition, the morale of all countries declines by 1 at the ends of turn 1 and 2, by 2 at the ends of turns 3 and 4, and so on. When morale drops below -10, the country is considered to be in a state of disorder and must roll every turn before each attack. If the roll is a 6 then the attack does not take place. If morale drops below -20, then the country undergoes Revolution. The country loses its turn and its units turn hostile to all. This counts as +3 morale for each enemy and -4 morale for each ally. The United States does not suffer from morale loss while not at war. Victory conditions are: Allies force out 2/CP force out 2 (Armistice), Allies force out 3/CP force out 3 (Capitulation).
Unrestricted Submarine Warfare: When Germany declares USW, they roll a d6 every British and American collect income phase for each submarine in a USW zone. IPCs are subtracted from the corresponding Allied power for the total number of the dice roll(s).
Königsberg: Germany starts with 1 cruiser in Sea Zone 26.
Askaris: France, Britain, Italy, and Germany can raise Askari units in certain African territories. They can buy max 1 askari per territory per turn. Askari units have attack of 1(artillery 2), defense of 2, movement of 1, and cost of 2. Germany can raise askaris in Kamerun, German East Africa, and South West Africa. France can raise askaris in French Equatorial Africa. Britain can raise askaris in Union of South Africa and Nigeria. Italy can raise askaris in Somaliland.
Naval Flight: When an attacking power in a naval battle chooses to disengage and retreat, the defending fleet rolls a d6 against it, scoring a hit on the retreating fleet with a 2, if the defending fleet has no cruisers, or a 3, if the defending fleet has cruisers.
Spain: When Spanish Morocco or Balearic Islands are attacked by a power, Spain spawns its artillery and 7 infantry under the command of a power of the opposing alliance to the one that attacked the Spanish dominion, and Spain is now allied to the power that commands its army.
Seaplanes: Fighters may fly out to sea and grant air supremacy to battleships and cruisers in the sea zone the fighter(s) is in. Fighters attacking this way do not get to strafe, and can only do this if there is a transport with space in the same territory. The fighter provides air supremacy allowing allied battleships to attack at 5 and allied cruisers to attack at 4. Once combat is over, the fighter must land on a transport and become cargo.
Repair Work: Damaged battleships can be repaired at a cost of 3 IPCs.
Swiss Alps: Switzerland is impassable.
Rail Lines: During the movement phase of your turn, move as many of your units as you would like from one friendly, uncontested territory into another friendly, uncontested territory. The two territories (the one you are moving from and the one you are moving to) need not be adjacent but there must be a safe path between them. This means that you must be able to travel from the first territory to the last territory through territories that you or an ally control. If you have to pass through an enemy controlled territory, a contested territory, or a neutral territory then you cannot use rail movement between the two territories. Rail movement is restricted to Europe, Constantinople, Smyrna, and Ankara.
Heavy Armor: Battleships cost 14 IPCs.
Hellespont: Sea Zone 20 is split into a northern(SZ20a) and southern(SZ20b) half. Powers must control Constantinople to cross through SZ20. Powers controlling Constantinople with ships in SZ20 are considered to be defending both halves of the sea zone. It costs two turns of movement to pass through the entire sea zone.
Torpedoes: Submarines have a first-strike capability.
Many of these are the creations of others, and I don’t plan to use every one of these. They’re all here just for speculation.