The Virtual Knee Surgery game as a window onto some gaming concepts

Your first task is to check the patient's vital signs, comparing them to healthy ranges:

After viewing X-rays, you are asked to mark the correct knee. I
found I actually had to stop and think for a moment, a great
demonstration of how easy it could be to get the site wrong. The tool
interface is a nice solution to the problem of simulating skills
online. This game does just enough to get the point across.

You click the right tool...

Then draw your initials on the knee.

After the patient is draped, and the incision is marked, you make the incision by dragging a scalpel down the marked incision line. The scalpel moves as if it is on rails, which eliminates the need for manual dexterity with the mouse.

On the interactivity spectrum, the virtual knee surgery falls nearer to the low end of the scale, similar to a story or movie. From one try to the next there is very little change in the way the game plays out.

This is an example of a "Progression" game. You are presented with a series of challenges, where all the options and solutions have been pre-designed by the games developers. You can't do anything they did not explicitly create.

Despite its apparent simplicity, this game keeps the player's interest and teaches some of the steps and associated concepts (like sterility, how the prostheses are fitted, vital sign ranges, etc.) of surgery and knee surgery in particular.

The Virtual Knee Surgery game demonstrates some contextual learning. The player is given a little scrap of new knowledge, which can be used immediately, then another for the next step. You have very limited options in how to use the new ideas, so you may not understand or retain as much as if you could try things out and fail some of the time.

In general, adult Learners tend to prefer more control over the speed and direction of the learning process, so that is something to keep in mind for designing learning games.

You will probably notice that there is really only one path through this game. If you make the wrong choice, you are soon steered back to the correct path again, with corrective feedback as shown in the diagram below:

You might recognize the similarity between this simple branching and the decision trees healthcare workers often use to describe their thinking processes and procedures.
For example, this was a decision tree used a few years ago for managing cases that might call for restraint.  Game developers working to create scenario based games, have found that medical educators  are very well equipped to work on these types of games - it's a good fit. 

Medical educators are used to presenting cases as complex, branching narratives and they often invite interaction requiring critical thinking and understanding from learners.