Glad you liked it!
I imagined the menu spotlight to be from the side (as it is in game), but we ended up implementing it like this. Good to hear it's cool either way!
The boss is fairly difficult! The sniper really is the unbalanced and unreliable tower (most damage by a lot). You'll need a couple of those to beat the boss. Typical winning strategy for TD basically. Either cover the end with lots of AoE towers or a point where everything comes together. I believe it's the center of the map on level 3. About 3-4 cannons should suffice. A cpl standard towers and then just spam snipers haha