A staff party at your own office is entirely possible and can even be a special choice when it's done well. But there are a few things to arrange properly in advance:
Transformation: during the day an office looks like an office. To bring in a party atmosphere, you need to invest in décor, mood lighting and furnishing. Remove or cover up everyday office furniture. Catering and technical production: offices rarely have a professional caterer or sound system. Hire both in externally. Sanitary facilities: office toilets are usually not equipped for large numbers at once. Plan this in advance. Permits: check with the municipality whether a notification or permit requirement applies for sound or alcohol at your location. Safety: escape routes, fire safety and first aid are your responsibility, not that of a venue manager.