Project Hospital: Hospital Services Review (Rumi)
Must buy DLC when buying the game. Hospital services adds Pharmacy, where patients can go and buy medicine after a check-up, there are other added sections like Lounges, Gift Shop (more ways to profit), including better Janitor Management (which is helpful to organize specific places for a designated janitor to focus in cleaning).
The DLC completes the "Hospital Atmosphere" at best, while the other 2 DLCs are department focused, which are more optional, and only depend on your interest -- however the department DLCs add way more content from furnishing to countless different diagnosis that creates way more gameplay variety, I personally bought Hospital services first because it irks me to not have a Pharmacy, and a better janitor management system since base game janitors are "random" in their cleaning.