Okay, here's the full walkthrough:
1. Grab the water in the Vault.
2. Go outside the Vault and get the rebar sitting outside.
3. Talk to Preston.
4. Go to the "Red Cock" (Red Rocket) and get the Barrel outside and the Frying Pan inside the open part.
5. Got to the radioactive zone and put the barrel down.
6. Get the Key.
7. Go back to Red Cock and open the locked door outside. Get the Coffee maker and the wooden board.
8. Go back to the radiation zone and place the wooden board over the open gap.
9. Go to the Deathclaw zone and get the pipe near the cage. Combine the pipe, coffee maker and rebar in that order and make a Power Fist.
10. Use the fist to destroy the cage. Fuck the Deathclaw and get the car battery.
11. Return to the Vault and use the battery on the machine. Release Piper and get the Lighter.
12. Go back to where the Deathclaw was and get the egg and combine the egg with the frying pan and the lighter. Give it to Preston and fuck (and obtain the key).
13. Go into radiation zone and you get bigger tits and a dick. Go to Piper and fuck her. Get the Fusion Core.
14. Go to the Assaultron at the Red Cock and activate (fuck) it. Get the duct tape.
15. Use the key and go into the other door that is locked at the Red Cock. Get the Spring.
16. Combine Spring, Water and Duct Tape to make a Ray Gun. Give to the Space Lady and Fuck.
17. Get in the car and the game is over... for now