Over quite some time now, I have been developing a set of Vietnam skirmish rules. One fundamental variable, in the different versions tested, has been to play the game either as an adversarial, player vs player game, or alternatively with all the players on the same side against the umpire (referred to here as a 'one-sided' game. A one-sided game bears more resemblance to a role-playing game than the more conventional 'chess with a thousand pieces' approach generally found in wargaming.

Both approaches, it would seem, have their pros and cons.

Benefits of one side played by umpire:

Better hidden movement
It is much easier to handle hidden movement. The players forces can all be placed on the table, with the enemy on a map for the umpire, and being placed on table as necessary. No need for dummy counters etc.etc.

Balancing scenarios
There is also a better opportunity for producing a more fun game. However carefully an umpire tries to balance a scenario, it often ends up weighted heavily towards one side. Alternatively a startling act of player stupidity at the start of a game can immediately skew an otherwise balanced scenario and leave that side with a disheartening struggle against overwhelming odds. If the umpire is controlling one side, then they can alter the course by reducing the level of opposing forces to achieve the ultimate objective of most wargames - an evening's entertainment.

Reduced arguments
Another area which can be improved is the amount of arguing interrupting the game. This is reduced with a one-sided game in several ways. First of all, many of the rule mechanisms can be known only to the umpire. If the players don't know the fine detail, they can't be rules lawyers. Second, because there isn't a competitive interest, the umpire can handle events in a 'common-sense' way which will generally be more acceptable to the players. Finally, if the players don't know what the hidden forces are, or what the rules are, they won't know if the umpire is ignoring/altering rules.

Disadvantages of one side played by umpire:

No competitive edge
The competitive nature of an adversarial game gives a motive and interest in playing that a one-sided game may lack. Although in a one-sided game, the players may compete against each other to gain kills etc. this is still not quite the same as grinding a human opponent's forces to dust. Whether this matters much will depend on your players.

Lack of enemy cunning
As the umpire, you may not be able to put as much energy and ingenuity into running the enemy as a player, who is competing against an opponent and is not distracted by running the game, would. This may mean that your tactics are a bit lifeless and predictable.

The final decision must be dependent on the personalities of the players and the period of war which is being simulated.