There are dozens of BitLife achievements. Each one can be pretty insane to get. Some are fairly straightforward, while others involve a lot more work. Some of them are just dependent on RNG, while others need you to put the time in. Earning the reward is never easy. This is actually one of the more difficult ones to get, as you need to be fairly wealthy to do it. Since you need to own a mansion to get the Mansion Party Achievement, you need money.
You have a few options. You could try and grind out the cash to buy the big house, but that takes a lot of time. You could try to become an athlete, musician, or social media star. Basically, you want to unlock the Fame system and earn millions doing book deals and the like. That’s a lot of work curating social media and managing stats.
The other intensive option is to be born wealthy. One thing I did was to curate this massively wealthy character, then adopt a bunch of kids. I spent time giving them tons of cash and fancy stuff to sell. When the old character passed away, I swapped to the younger character and earned the achievement. Another way involves a bit of RNG, as you could be born into royalty. That’s a lot less work, provided you get lucky and are born with the silver spoon in your mouth.
Click Activities, click Go Shopping at the bottom, and visit the realtor. Buy a mansion for a few million. Now you’re ready to throw that mansion party. Once you purchase a mansion, you then need to look under Assets to find it. Select the mansion and click Throw a Party.
Finishing this chain of events will earn you the Mansion Party achievement.