Ok. This is a short guide on how to beat it with ease.
1. For the first 3 days. Just get up about 10 on weps and 2 on survivors.
2. After this, you should have an UMP. This will help you for the levels until you get the chainsaw.
3. After you get the chainsaw, you don't need to spend points on healing your base or getting survivors. You just have to stand back and try to aim the chainsaw at the zombies heads. It kills them very easily.
4. By then, you should be on the Uzi or Hunting Rifle. If you have the Hunting Rifle/Chainsaw combo, try getting headshots with the Rifle. (One hit kill)
5. Keep using whatever combo w/ the chainsaw until you get the ak47. The ak47 is a decet weapon, I like it a little. But after a few levels after the ak47, you should get a Barrett sniper rifle. This is the ultimate gun.
6. From then on, you should have no trouble killing the rest and surviving the other nights with a good weapon combo.
i discovered something like a cheat or a bug. ex: ekip hunting rifle and chain saw. when de night starts, use thee chain saw and click in the mouse . when the chain saw is on, switch weapon 3 times. the chain saw will reload. now switch to hunting rifle and... WOW!!!! the rifle will be with 99 shots O.O its not a joke, beieve me