Skip the machinegun and go directly to the double machinegun. It's way more effective than the first weapon and it's not worth spending 2k on the single machinegun.
Also, when you've done updating something and the buttons gets greyed out, clicking again selects what is beneath the button: another worker (fine), another building (not fine if it upgrades it), an elevator...
Enjoyed it but some bugs: elevators seemed to easily disappear, I can't hire anymore (the buttons stopped working when I placed a cat, I think). Selling rather than destroying things. And needs something to handle hundreds of "workers": "upgrade all" in particular.
There's a problem with hats: I played before the kongregate badges were added and now, loading my save, I had "0/25 hats unlocked", but my party still has them. However, if I take one guy, remove his hat, I can't add it again.
When a tooltip is displayed, moving mouse over this tooltip and onto another element doesn't trigger the new tooltip. Especially noticeable for bottom buttons.
Also, when holding positions, catapults stay a tiny tiny bit too far to reach melee ennemies (provided yu have melee units in frontline yourself too).
Otherwise, nice game but only started a few minutes ago. :-)