I love that you have France going first, and I think your changes to the unit stats (cheaper cruiser, strategic bomber doesn’t massacre ships, etc.) are several steps in the right direction.
I’d encourage you to spend some more time balancing the value of your techs against each other. I enjoy playing with techs, but a common, valid criticism of A&A Revised Edition was that if you rolled Heavy Bombers or Long-Range Aircraft, the game was yours, and if you rolled Rockets or War Bonds, then you wasted your money. The “roll at ever easier targets until you discover something” solves the problem where you might not discover any tech, but it doesn’t solve the problem where some techs are worth much, much more than others.
Imagine, for the sake of argument, a nation that’s earning about 65 IPCs / turn. Could be Germany, Japan, USA – doesn’t really matter. A major power. Efficient Industrialization tech is worth at least 16 IPCs / turn to that major power, even if they don’t alter their strategy at all. If you build something really balanced and ordinary like 4 inf, 2 art, 1 tnk, 2 DD, 1 CV, and 1 ftr, you save sixteen IPCs because of your new tech. Every turn.
Now let’s take that same 65 IPCs and see how it benefits from Improved Artillery tech. Well, you could get away with building 5 inf, 1 art, 1 tnk, 2 DD, 1 CV, and 1 ftr, for total savings of 1 IPC per turn. If you really wanted to stress your artillery advantage, you could build something like 10 inf, 3 art and save 2-3 IPCs/turn. It’s just not in the same league as Efficient Industrialization. It could be useful for Russia if you’ve already built a huge stack of infantry and you need an offensive boost NOW because you’ve run short on artillery with which to trade territories … but I think Russia would still much rather have the Industrial advantage, because with the savings from Efficient Industrialization, Russia could just buy more infantry and more artillery.
So, yeah, my advice is to look at each of your techs, calculate the rough value in IPCs/turn that each tech represents to a major power, and make sure they’re within a few IPCs/turn of each other.
Specifically on the Heavy Tanks thing, I think your idea is really cool, but I agree with ammantai that heavy tanks historically were crazy expensive and could not be manufactured in strategically significant quantities. They were also no better than medium tanks at mowing down infantry – you only needed heavy tanks if you were fighting against medium tanks. With that in mind, here’s how I would reword Heavy Tanks:
“During land battles, in each round of combat during which both you and your opponent have at least one tank, you ignore the first casualty inflicted on you (if any).”
That way you can’t use a tank stack to (unrealistically and annoyingly) absorb a dozen hits each round, but your tanks will still fight better than your opponent’s tanks in a way that’s fun to exploit.