Does the hectic aspect seem balanced? And if not, what aspects aren't? For example, enemies being too quick/slow, etc. Is the balance between using stardust for towers and using it to feed the blackhole sufficient? - I thought the faster-paced part of it definetly works, and brought in a much-needed difficulty scale for the game. Bloons, after a certain point, becomes very easy and mindless, but with that quality of being stressed, it really helps.
Do you have any particular ideas for towers? - Personally, I'm not super creative, but something along the lines of Zodiac creatures would be cool.
What different terrain/level topography ideas do you think would be fun and interesting? - I love the themes of water levels, so maybe like blues, pinks, and greens to show coral reefs or something similar would be cool.
Does the flow of the game feel moderately smooth, and in what ways if not? - I think it feels very smooth and fun to play.
Is the UI intuitive and understandable? Any comments on adding/removing/clarifying anything to it? - Maybe it's just me, but it took a solid 3 minutes of trying every key on the portal thing to realize that it can't be moved. I think a tiny tutorial, or some little text boxes would be great.
There is currently no elemental effects/immunities implemented, so besides these, what kind of different behaviors might be interesting for enemies? - So far, I think the varying sizes are a great touch, but I like the idea of splitting enemies, like slimes in Minecraft.
Did you find any interesting strategies during your gameplay? If so, please let us know what you found, and if not, tell us how we can give you more opportunity to strategize. - I couldn't get anything crazy down, other than a basic Overcooked schedule of moving back and forth effieciently.