Wow. Rarely does a game 'combo' type game like this not infuriate me. One of my favorite games that I've played on this site. I'll keep my eye out for future games from this developer.
Weird glitch: If you kill the last two locusts before you kill the first Re-encarnie then he never gets 'killed' by the taxi. He just lays in the street and all of the buttons are unpressable.
Decent, really easy game. I found the archer/mage upgrading to be redundant. I mean, you have to buy an upgrade that allows you to upgrade? (Or maybe I misunderstood it)
Total pop is the max number of that type of ally in battle. The total pop of a hero is 1, so you can only have 1 type of that hero in battle.
Retreat is for selected units and Fall Back is for all units.
Easy way to get the last achievement:
Go to any arena map. Get the Grenade Dart Launcher asap. Shoot in the head, then double jump. You'll get more points for midair headshots than normal. I had 5,000 points at just under 100 kills, i believe.