Make sure you guys are detonating your horde when theres ~100 villages left. It'll maximize bones from the 1000 or so zombies you created that level, while still maximizing the amount of caged zombies you can sacrifice / release the following round.
It's good to upgrade all troops even those you don't use once upgrades to your main troops start slowing down. They start out very cheap and will add several levels each time.
Things I would like to see in the next update that haven't been pointed out in the top comments yet.
1) I want to see who I've traded crates to, a "crate log" or something of the sort would be appreciated
2) I want to know how many rounds are in a tile when I click on it, before I start it
3) Finally, fix the lag, of course
I am currently playing this game on my labtop and it won't fit on the screen. I'm not sure if anyone else has this problem but a full screen mode would be great.
There could be an option for something to do once we have purchased all the managers, for example we could have the option to click and it would bring in more money than the managers would normally make. I know this is supposed to be an idle game but it might be a fun idea to keep people on this game for more than a couple minutes at a time.
 "Incremancer")
 "Shop Heroes")
 "Frozen Islands")
 "Bloons Monkey City")
 "Egg Knight")
 "The Enchanted Cave 2")
 "Royal Squad")
 "Caravaneer 2")
 "Sentry Knight 2"){kind=logo}
 "MadBurger 3")
 "AdVenture Capitalist")
 "Clicker Heroes")
 "Rogue Soul 2")
 "Kick The Critter")
The "Hearts" are earned from selling, complimenting, and discounting items. :)