You mean the Desert Commando II console in the disco? That's just there for fun, you don't have to beat it.
You get the BUF password from one of the guys on Sophia's party. Getting the party to start is a rather long series of sidequests, how far along are you? Here's an overview of things you need to do:
*Talk to Sophia near the power station and agree to help her
*Help her clean up around the house (bottles and plates)
*Talk to Ben about the music for the party
*Get up on the town wall on the right and talk to Natasha near the castle
*Talk to William Bockbeer (the poet living next to the comics shop) and agree to help him find his hedgehog
*In Sbrodj, talk to the cook in the palace
*Go out to the battle area on foot and enter the small cave you can't enter while in the tank
*Have the tinker fix the cook's kettle (a cn of tar can be found in the cave with the mutant slime monsters)
*Find the hedgehog in one of the ruins in the Black Forest (you'll need the gloves the cook gave you to pick it up)
*Bring the hedgehog to Bockbeer, then bring the poem to Natasha
*Talk to the candle makers (the guys wearing black suits and hats) in the restaurant and deliver their candles to the castle kitchen, they'll give you a slab of wax
*Meet Natasha and her friend in the castle's grand hall
*Go downstairs and have a look at Ulf and his instrument
*Go up to the computer room and read the entry on the thorbaldophone in the library computer
*Use the wax on the thorbaldophone
*Tell Natasha and her friend about your success
*Bring the CD to Ben
*The party starts after you've slept one time, the easiest way is to go upstairs and sleep for free
*Talk to all the guests on the party, you'll get the password and a couple bonus items
Let me know if you need more specific help with any of the tasks - I had forgotten how long and complicated that series of quests was
