I'm glad someone agrees that the industrial age redoubt is just a laughing stock. Sure, it's awesome in an Arnold Schwarzenegger kind of way, but I even this seems a little too silly for the game's tone. It would be far too much work to replace the artwork at this point, but every time I see that guy standing on top of a random metal tower. (For God knows why) I just always think... Shoot him. Just shoot him.
That being said, my long escapades in the streets of Osaka have taken away from most of my game time now that I've hit Industrial age. I'm finally playing at the level that I was playing at with other strategy games, which means more days between upgrades. You raid for resources, upgrade, and screw around with medal climbing when there's nothing else to do. Since this is just a mobile game, I don't concern myself with extensive play time outside of upgrades and minor medal climbing, but the Industrial Age has definitely made me feel like I'm getting a break from frequent playtime due to longer upgrades. The upgrades times are understandable in this genre of game. (For me) I actually like taking pictures of bases and watching them grow over a long period of time. Overall, I love the designs for the Industrial age, everything looks great, even though I hate the redoubt tower, it looks pretty. (Previously my favorite defense because of the gunpowder/enlightenment design) I felt that enlightenment was incredibly boring because of factory troops being relatively boring, and the design not really changing between it and gunpowder, which in my opinion is the most exciting age.
The design team has a real knack for changing the foundation of a defense and that's it. I wish there was something else added to make it more menacing. It's just a huge let down to not see things change, and I'm afraid that the Modern age may suffer the same treatment in relation to the Industrial Age. Obviously, this eases some stresses during production, but the end result would be much more satisfying if more time was taken into designing these upgrades in more detail.
I think that these later ages/town levels/city levels and so on, are complemented by things like alliance wars, so the long upgrade times are eased because you have something else to do.
The future looks bright. Stay dominating.
And one last thing adding on to another posters comment.
Having a steam train could be interesting, and could be used as a way to get additional resources or trade goods. I won't mention other games, but there is one that takes advantage of sending a vehicle to a place to get resources, and also is useful for dumping resources that aren't being used as frequently. (Food) lol
Obviously, this would require long hours of labor, and as I ask for far too much from the design team, I will settle for whatever comes through the pipe.