Thank you so much for your thoughtful feedback! I'm glad to hear that you like the art style and see the potential in the game as a mobile hit. > v<
Regarding the material collection system, I appreciate you bringing that to my attention. It sounds like there's a bug where materials aren't being collected as intended, it happens because of a 2.D style I'm going for make a cursor fly far away from the map when you zoom out ;-;
—I'll definitely look into that and work on a fix.
As for the ultimate skill that makes your base smaller, you have to purchased the "Compression Knowledge" first, thankyou for pointing out that it might need some hit on that. ^^
Your point about the difficulty scaling is also very valuable. Balancing the game so that upgrades are accessible at the right times and that difficulty progresses smoothly is key. I'll be tweaking the upgrade costs, increasing material drops, or adjusting the early waves to ensure a more consistent experience. ;>
Again, your feedback is really helpful, and I’m excited to continue refining the game. Thanks for playing and for the kind words! ;D 💗