Crime Boss: Rockay City

In order to obtain assets, you will have to obtain enough money by either running jobs and heists, or by selling obtained valuable goods (located within your stash) on the black market. Some assets may only appear on certain re-runs of the campaign, some will also be given by characters. Below is a list of the 26 possible assets I have seen, however, you are only required to purchase 25 for the achievement. There may well be more than this, but I never played beyond the requirements for this achievement.

1. Office Upgrade I
2. Table Lamp
3. Phone
4. Wooden Easel
5. Rugby Trophy
6. Cigars
7. Modern Lamp
8. Vintage Camera
9. Terrestrial Globe
10. Leopard Coffee Table
11. Whiskey Set
12. Priceless Ming Vase (Red)
13. Philosopher Figurine
14. Medieval Sword Collection I
15. Telescope
16. Ethnic Mask I
17. Priceless Ming Vase (Blue)
18. Medieval Sword Collection II
19. Ethnic Mask II
20. Rockay Helmets I
21. Piano
22. Ancient Statue Torso
23. Lion Sculpture
24. Croc Table
25. Penthouse
26. Tropical Island

Tip:
If you own the DLC ‘Dragon’s Gold Cup’, you can speed up this process a little as you start off with a much larger sum of cash. Simply purchase any assets you can, then just continue re-roll the campaign (rinse and repeat) until you have purchased all possible assets.

In Baker's Battle (single player mode), you need to purchase 25 assets in total from the office tab of the menu across all playthroughs. This is also a good way to level up your boss. Item selection will be randomized every playthrough.

The Dragon Dogs from the heist of the same name count as an asset if you decide to keep them instead of selling them. Items procured through Casey's missions in the campaign (for instance a car, penthouse, or a grand piano) also count.