Honestly… SuperSubs suck so much. Here are a couple things that could be done to make supersubs better:
Attack at 3, defend at 2 (simplest solution, but might be too powerful, thought I doubt it would still be more powerful than heavy bombers, or paratroopers,etc.)
Attack at 3, defend at 1, cost 1 less (so they would cost 5 instead of 6 normally, or 4 instead of 5 if you also have improved shipyards)
Attack at 3, defend at 1, may hit airplanes, and may be hit by airplanes unless user chooses to submerge them (could be interesting)
Attack at 3, defend at 1, unaffected by destroyers (may pass under destroyers, may submerge from destroyers, destroyers do not take away 1st strike ability)
Attack at 2, defend at 2, cost 2 less (so they would cost 4 instead of 6 normally, or 3 instead of 5 if you also have improved shipyards)
And lastly, Any combination of the above.
What could make Adv Artillery better? Or at least more interesting?
Instead of upping the attack power of one extra infantry, Adv Artillery may now be used to “bombard” an adjoining territory. This uses up the movement points of the artillery, so you can not also attack with the artillery after you bombard. Works just like a Naval Bombardment except you do not need to attack the territory you are bombarding to be able to bombard it with Adv Art. (example, germany has 2 artillery in Ukraine, and 2 artillery in the Baltic States, Russia has infantry in Karelia and the Caucasus. Germany decides to bombard both Karelia and the Caucasus with its artillery, and also attack Karelia with 5 tanks, but not attack Caucasus. Germany rolls double snake eyes. 2 russian inf in caucasus die immediately since there is no attack there. in Karelia, Russia moves 2 infantry to the casualty space, where they will still get their rebuttal against the german tanks. Now the german tanks and russian infantry get to roll the rest of their battle.)
War Bonds is boring and not very useful, while Rockets is a bit more interesting because you can purchase additional AA guns / Rockets (AA guns should cost 5 each again). War bonds could be made more interesting by allowing the person who own’s war bonds to purchase additional War Bond dice for 8 IPCs each (takes 2+ turns to pay back). (Germany gets war bonds on a research roll. Next turn, they choose to purchase 2 additional war bond dice for 16 ipcs total. at the end of their turn they will be rolling 3 total war bond dice, at 1d6 each, to determine total money received)
Improved Shipyards is crap if you are past the 2nd turn and are not the USA and you are not attacking Japan. That is a lot of IFs, which means Impr Shipyards sucks. How about this, when you get Impr Shipyards, you ALSO get a free Carrier next to your factory at the end of the turn? That might convince, say, germany to try it out.
Radar is useful only for Germany, Italy, and Russia. And 2 of those will never ever be able to afford researcher dice, so that means Radar is only useful for Germany. How about this: Radar also improves the defense of Carriers by 1. Or alternatively, Improves the range of all Fighters you control, that began their turn on a Carrier you control, by 1-2 (5-6 movement points instead of 4). Or another alternative, all your cruisers or carriers also count as an AA gun, so they get to take an AA shot at the beginning of battle (limited to 1 per territory, just like aa guns). Or another alternative, America starts with this tech that way they never have to worry about getting the most useless tech for them.