Thank you again for taking my suggestions into considerations :)
Sorry that this is whole back and forward XD
BUT I had some suggestions for the left path for Mouse Trap final upgrades.
I had mainly two ideas that would made them more useful especially late game as I've noticed that they tempt to get destroyed quite often before having a chance to do any real damage, I've did came with a smart idea that you might like.
Pretty much the last two tiers I call "Camo Traps" Two variety of traps that work differently depending on your playstyle, their main benefit? INVISIBLE to common enemies, making them able to last in the battle longer as well making them more resource efficient.
Spike Trap - Shoots out bunch of spikes out of the ground dealing splash damage to all enemies, before slowly receding back to the ground. It is a slow but powerful trap that cannot be seen by most enemies and takes a long time to recharge, but destroys tanks VERY efficiently.
Barb Wire - Turns Bear Trap into a constant dealing unit that does Tiny amount of damage to the enemies but applies "Slowing effect" that makes them move slower as well take constant contact damage. Mostly useful for slowing enemies down but is invisible to common enemies thus able to support other units on the battlefield.
NOW this would all be great but it would certainly be broken, units with no drawback? Well that's where I had the idea for new enemy concept.
Specialist - A slow tanky Roomba with bunch of gadgets and tools strap to it, it thinks that is very smart and clever like The Scientist Roomba but in reality, they just learned to look down. Specialist Roomba's have the ability to locate and dismantle Camo Units, and destroying them instantly. On top Sniper Rifle Units will actually prioritize them to be shot down.
I do hope these will help out with the units and suggestions :)
I had a idea for a completely original unit myself later on, but again its your game and I am just really spitballing ideas here since I am enjoying myself so much XD
Thank you again and have a wonderful day.