Mortars are completely stupidly OP to the point that going anything but Mortars is just throwing. The Weapon that gives all projectiles infinite pierce at the cost of -60% damage doesn't give Mortars pierce, just gives them -60% damage. Which to be fair, it would be gamebreakingly OP if it did work. But the bow with 2x projectiles does work with them, which is about as ridiculous.
Wave 1 feels completely imbalanced. If someone gets a high HP projectile unit they just win. Nothing else you do, can possibly get enough damage onto it, to stop it winning in Earthquake automatically, essentially.
Earthquake overall heavily punishes going for multiple low hp buildings. Since it's quite common to have the enemy on a single Ammo 3x slot thing, while you still have several damage buildings left, then still lose in Earthquake earlygame. Simply because they have a 300-900 hp brick (if they have that one helmet), that just auto-wins on time.
Going units at all only seems viable if you high roll your items to an insane level. Otherwise you just get all your buildings Mortared before they can do anything, since you can't exactly barricade the entire top of your base and still actually be able to produce enough units to even destroy their 2-3x Barricades before Earthquake. Let alone destroy their actual mortar/ammo setup. I think I've lost one single round to units going mortars, ever.

















