General feedback/opinion on crystals, towers and items used on towers

[アモWモモシ]

When it comes to the crystals, it would be nice to easily change them out on towers, per now you have to buy a second tower if you want to change it, but the ability to change out, even if you dont get any refund for the crystal would be nice, maybe have this as an option in game in terms of difficulty?

Towers, along the same lines as the crystals, would love the ability to sell or atleast remove towers as the economy isnt that big of an issue when its beeing played the right way

And the items in the inventory, the limited space or ability to trash things in the inventory in any way makes it a pain to manage as i have to buy new towers just to store excess items when i get far enough to not loose high end items when they arrive

And another thing in general, the tech tree is pretty nice, but completed it in 6-7 hours, maybe make the progress a little less fast by either make leveling going slower or make unlocking certain things or branches have cost going up by one or two points maybe