If you came up just short in the end and want to try the last level again don't click back to main menu, go to another website and then come back. It will have reloaded your save and you can try the last level again.
Pretty good game, kinda long though, but it made me laugh. I kept failing the hard badge until I changed my setup to Ice Sword + Ninja Headband + Leather Bracer + Walkman, then I got it first try at level 17.
If you want to stand a chance on hard you need to buy all the resource upgrades asap in the beginning so you can get tons of firepower for the final level.
This game is really fun but if you play it smart it's pretty easy. I was using Barrier Decoys, Spread Gun and Damage Buffers and I was killing things before they got on the screen in the last campaign.
That final hard badge is so brutally long. Tips: keep your order tickets in order of what oven the pizza is on left to right so you don't have to keep track of that. Remember short-medium times always, but long ones you can forget about for at least 2-4 orders. If you're going for the final badge and want to save time just make your already gold star customers an empty pizza, you will lose their stars but you will never lose their gold, this way you can save a lot of time and energy while only having to focus on non-gold customers. Still takes forever though.