Customisable sandbox difficulty parameters

The ability to adjust difficulty parameters for sandbox levels (and adjustments in general to sandbox levels) is a big part of providing replayability for the levels.

After going through the set of campaigns and sandboxes, being able to increase things such as needs depletion, patient spawn rate, health deterioration rate, staff skills, cash earned, research speed etc. provides reason to go back for endless tries of the same set of hospitals once a player has mastered the techniques to complete the original set.

With such things available it makes it easy to lose hundreds of hours in the game tweaking and challenging yourself as you see fit.