Hey! Just got done with the game so far (v9.2). Overall a solid expansion of the first game! You seem well aware of the odd difficulty curve, which is about the only major issue I can see with the game so far. The characters, the dialogue, the art, and ESPECIALLY the sound design (the suit creaking is probably the best thing I didn't know I needed) are fantastic, as far I'm concerned. Really looking forward to playing the full release.
I could see an attack timer (or maybe a building or suit upgrade that gives you one) being a great addition, since I found myself waiting around for the next wave before starting any serious expansion projects. That and maybe more indication of things stats. Health bars for the slimes? Posted numbers for the attack power of defenses and the drone? Having energy consumption added to the description of every applicable building would be good, too, like the radio tower and teleporters. Just quality of life ideas. You've got a lovely game so far, thanks for sharing it with all of us!
(P.S.) Oh I nearly forgot! Sen seems to gradually lower throughout the playthrough. It must be very incremental, since he maybe halved in altitude over the course of 11 hours, which was when I finally noticed. I'm afraid I don't have much more info than that.