Disclaimer: Not Sure if discovered by me. i didn't do any research.
Important: The people next to the stove can NOT have the ray gun or any other explosive weapons.
1. Open The Green House.
2. Take The Stairs.
3. Do NOT Open The Other Down Stairs Door.
4. Save up 3000 to buy the truck.
5. You or your other team mates need to buy semtex grenades.
6. Have one player go in the garage inside of the green house.
7. Have him hold the semtex in a corner and look at the ground.
8. Have the other 3 or the amount of people your playing with go stand next to the stove in front of the door that you have NOT opened.
8. If done correctly, all the zombies should pile up next to the player in the garage with the semtex. The players can shoot the zombies.