It's a great game that I've enjoyed playing again (I died at wave 11). Always a pleasure to play Tower Defense, well done to you both!
I like the plant heads, they're cute and funny at the same time. The variety between the opposing plants and our own is great!
TIPs are a good thing.
Having the calm sound of nature between two rounds is an idea worth keeping, it allows you to clear the air between two rounds where you hear a lot of gunfire, but then there's a lack of background music during the rounds!
I've often had the same upgrade 2 times out of the three offered, which is a shame because you have enough variety to offer 3 different ones!
I didn't quite manage to differentiate between the mechanics of the cactus and the carrot, so maybe there's an accessible place that explains their speciality (or a tutorial if you want to polish it up).
At one point, all my gunflowers disappeared, and it was really hard to get back up after that!
My meta is: Gunflowers at the back + Box hedges at the front in staggered rows to prevent the whip flowers from hitting all my Box hedges + bees upgrade + Box hedges cost decrease upgrade (wave 11). Still, I find that early sunflowers aren't very profitable, while box hedges are banger! I tried to use carrots and cactus, but found them too weak in early.
Maybe with upgrades it's cool (that's what I get from looking at what some people have played).
And I've seen a minor bug: when you click on one of the plant choices at the top of the screen, just before the round ends or just before you die, the mouse icon remains with the image of the plant you've just selected. I thought it was a cool bug, and a cute cactus icon!
By the way, it's a very nice game that could perhaps do with a little more readability in general (the terrain lines are a little blurred, for example).
Well done again!
Have a nice dev !