I enjoyed playing the early stage of this game but I quickly gained so many resources that there was never any challenge. Finding the right balance is difficult but very important for a tower defense game and right now I feel this is far too easy. To me, it felt interesting to place the first few towers strategically but then I realized I could just spam them without thinking. It also never felt like an interesting choice of which tower I should be upgrading and I never understood what their benefits were when incrementally upgrading so it didn't feel as impactful as I'd like.
The combining elements mechanic seems interesting but again I had no idea what the elements do or even how much better those towers are compared to one another. I'd love to see some stats and maybe damage numbers so I can feel the impact of my decisions more.
Overall it works as a tower defense game, but it left me wondering why I would play this over another tower defense game. The combining elements seems to be the most unique factor but it's unclear to me what the elements do. I'd love to see the choice of which elements to be a big component of the game. Certain enemies could be weak against others (and maybe they already are and it's not displayed clearly), and maybe certain elements have different attack patterns/ranges.
Overall this is a solid jam game. If you plan on continuing development I would definitely recommend figuring out how to lean into what makes this a unique tower defense game, and of course finding a way to balance it so it's not too easy to just spam without thinking strategically