As an avid fan of tower defense game 2 main things to improve the game a lot:

• Have the tower's stats be indicated by actual numbers and the increase from upgrades also indicate the change in stats. Tower defense games are games of tactic and planning, so you want to give the player as much information as you can, so they can feel satisfied with the decisions they make.
• In normal Tower defense games, the next enemy indicator generally allows for some time to plan, though in this case it seems to indicate the next enemy about the enter the field, which isn't really useful information as you'll know in a second anyway.

I like the use of the theme, as it is applied fully into the gameplay. The towers being monsters that are altered by the elements is a nice thing to play around with.

Also I dont think my base any health or can be destroyed.... atleast dont see a health bar or anything.

If you want some good inspiration for Tower defense games that implement some crafting/elements, look for Elements TD on Steam or Gemcraft (which is an old flash game)

Overall well done, the game is nice and playable

Great idea. Tbh, we also had something similar during brainstorming :D I really liked the twist about paths changing. Elemental description was also very handy (Most games want players to explore it). Credits, start screen, how to play , difficulty select were executed perfectly. Loved them!

I did notice a few small things that could be improved:
* I didn't feel the progression. Like towers get leveled up but I don't feel/see it. Maybe some more idea into it or visual indication (Like fireworks on level up or something :D)
* Tower level progress confused me. I thought its HP. Might want to change the visual concept of it a bit, like adding extra icon or label "EXP: " or even text instead of loadbar (or % above loadbar)
* I didn't understand if my castle is being damaged or not. Monsters were hitting it but didn't get any feedback (Nor damage taken, nor HP left)
* Very minor thing in elemental description, you have: "Fire + Lightning - Something". My brain automatically starts thinking math with that dash at the end :D Maybe replace it with | or something like that? :)

Overall very good job!