Too build on Vikings point:
I find too many organizers try to over complicate the games. Find keys to missiles, find three components bring them together, or some other co-ordination of tasks that mostly never end up being accomplished. That is not to say it cannot be done but for bigger games it becomes very hard to control.
Most teams knowing their objective before they start would bring the necessary tools to accomplish a direct action mission. Having to search and find these does not add to the realism and many times leads to frustration. The goal is to close with and destroy the enemy, second capture any intel or an objective, take it, hold it or take off to fight another day.
These types of games are the most fun because you focus on tactics (Patrolling, CQB, Defense, Ambush) instead of running around looking for a key to open a box before you can move on.
This is just an example but the most fun I ever have is when the objective is to eliminate the other team and keep them from eliminating you.
Cry Havoc, Let slip the Dogs of War!
"Opportunities multiply as they are seized."
- Sun Tzu, The Art of War