Some neat ideas here, and the game really reveals itself over time as you open up the mid and end game upgrades. Opening up board slots feels very good as that allows you to make stronger and smarter plays, an alternative to how the genre tends to just hand you multipliers for growth.
One of the mechanics that was the most interesting was having card removal as a card itself. It was a good way to enforce the positioning-theming even harder and worked well. Unfortunately that did make me scared to use the green automation later on, as that would've crippled my deck over time I'm sure.
While lots of bold ideas, at the same time some ideas clashed. I know you were looking to find more upgrade vectors for each color, but some of the idle waiting mechanics clashed with such an active game. Luckily that stuff gets obsolete over time, so I suppose there is a nice pain point removal once you get those upgrades high enough.
The end game cards are really fun to use and there's a bit of thought in figuring out how to balance your deck (as any deckbuilder should). Like you said in your description, there's a few builds and strategies and that keeps it all interesting. Nice work :)