You're a lone commando behind the enemy lines with a mission. You are full of guns and stuff but you're completely surrounded by enemy soldiers who will hide behind shit and jump over mines. You shouldn't walk over mines and should always keep an eye for hidden soldiers in the enemy's territory. Destroy their weapon farms and kill all the soldiers that get in your way. You might run out of ammunitions during the mission but you can still use your knife to continue your massacre. The number of soldiers multiply as you move up levels.