I've found great strategy for the 6-people setup: spam Taunt Germans for the first little while when you get 2 points per wave, and get a jeep to park in front of your soldiers. Send the shittiest ones out front to die; get a mortar and put it behind the jeep. An officer too. 3 fighters (riflemen work fine), 1 mortar, 1 officer and a jeep in front will let you rake up the TP's for whatever purpose you want them for (Most notably replacing the shielding jeep with a tank, or replacing a crappy fighter with a jeep behind the tank)
PiousFlea: I found it insanely hard at first, too, before I found out how to look up gem combos. While you're playing, click "menu", and it'll show every gem combo you've discovered in all the games (won or lost) with three question marks for those you haven't made.
If you aren't strong enough to defeat the huge waves of strong monsters, than you shouldn't be complaining. Often times your 8-second arrow stream or a titan unit will easily get you through it unscathed.
Guess you fail, decromancer :)
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