Its quite a violent game with tons of strategy needed in order to keep your soldiers alive, what your doing is protecting what I'm guessing is an allied base from the invaders (Nazis), it is small squad tactics with a 7 man rule (if you go over 7 men really bad things will happen, such as multiple airstrikes), your goal is to survive as long as possible, there is no end and there is nothing that will suddenly come in and save you when you are close to death.
The motto of the game site is "BECAUSE WAR IS UNFAIR" meaning this game will do its best to kill your squadron, it can send a pak38 (which is like a large cannon that fires very explosive rounds) on round one killing your team instantly unless you figure something out.
Give it a try: http://www.mudandblood.net/mudandbloodz.html
Think of this as a tower defense game only a bit harder, I seriously and strongly suggest reading the instructions.
