You choose to play as a male or female nurse, recently graduated from the University of California, and start your career in a small medical ward in Maryville. Finding a job wasn't at all hard, and you soon find out why - you're the only nurse on call.
Gameplay is virtually identical in all platforms, being that the main differences between them come in the shape of rendered 3D visuals for the Wii and PC, while the DS sports pixel-art type 2D graphics. The music and much of the sound effects are also different between the handheld version and the others, a more bleepy old-school approach having been taken in the DS while the PC and Wii feature a more hi-definition approach. A few of the treatment machines also differ between the DS and the rest, but in the end the gameplay remains virtually the same, sporting no platform-specific mechanics.
Through a quick tutorial you learn the basics: patients must be taken to triage/diagnosis, and then different treatments will be in order using your DS stylus, Wii-mote or plain mouse.
Some patients demand more attention than others, and your limited equipment, when compared to the large and continuous flow of in-patients, means you have to juggle treatments, prescriptions and clean-up phases. An unchanged Quick Treatment bed means no other patients can use it, which can quickly lead to a high number of angry patients. If you let too many leave in wrath, then it's bye-bye money and try again (you are fired over and over, but they let you at it again since you're the only nurse available anyway).
Hysteria Hospital: Emergency Ward sports a casual atmosphere typical of Time Management games, something which is also reflected in the level of content and customisation available - add new sets of medical equipment to increase the number of patients you can treat; patients for which there is no treatment available can be sent to another center by means of an ambulance; buy items to keep in-patients happier for longer; and last but not least, change the color of your work uniform.
There isn't really much beyond this, and in the later, multi-floored levels you'll find yourself spending as much as you can in order to tend to the highest number of patients as humanly possible.