You can have any number of players. You pick Nerf guns, and shoot each other for a time limit, or pick a frag number.
(this is a very good training exercise)
You stand in a hallway, or in two rooms with a door between them. You want it to be kind of far apart, about 25 ft or something. You can make it shorter, if you want, to make it a lot harder. You should play with guns that use the same type of ammo, or if you want it to be super hard, you can use guns that do not use the same kind of ammo. There are a lot of rules, so get ready.
To start the game, you stand somewhere in the hallway, about 20-25 ft. You then pick a Nerf gun, probably with the same kind of ammo. You make an imaginary circle around you, and you let your apponant see where you are standing. You need to get a good look at where they are standing. You then can begin. Make sure that you both have about the same amount of ammo. The point is not to be hit. You may block with your gun, and dodge bullets. You may run around picking up ammo, but you may not shoot when you are out of your imaginary circle, nor may you reload, while you are out of your circle. If you do you, you the other person catches you, you must sit down for 15 seconds, and give all of your ammo to the other person. While you are in your circle, dodging Nerf bullets, and shooting, if you are hit, you must sit down for several seconds, depending on where you get hit.
Head=10 sec
Chest/Back=7 sec
Limb=5 sec
When you get hit, you must stand up, and hold you gun in a way, that you cannot fire it, or load it. I.e, with the Lock n' load, you would flip the gun upside down, and hold it on one finger by the trigger gard. You then count out load, so that the other person can hear you, to the number to which you were hit. i.e. I got hit in the leg. 1.2.3.4.5. There is also no holding ammo, like not shooting for a long time, until you have all the ammo.
This might sound boring, but believe me, it is not. There are several version of this CtF. (Capture the Flag) You can play with hit limits, or just when you get hit, you sit down. Here are some of my reccomened rules.
Play in an open space, about any where from a yard size to an acre of space, depending on how many people you are playing with. Make teams that are fair, and that will make a good match. Divide nerf guns fairly. Use something as a flag. It helps, if it is a flag or cloth of some sort. You may stick the flag any where so that the enemy can reach it with out climbing anything. The flag cannot be attached to anything. So you cannot tie the flag onto a tree. Find a half line. Behind this half line (in your territory) you are safe. If you are shot when you are in your own half, you are safe and the hit does not count. (to add some more fun and challenge to the game, add the rule that the person with the enemys flag who is running back to their side, has to run all the way to their end line to win) You may shoot on your own side, but if you ammo croses the line, and hit an opponint when he/she is on their side, he/she is safe, and you just wasted ammo. The only time that you are allowed to shoot enemys when they are on their own side, is when you are on their half. So lets say that I am going for the flag. I run onto their side, and then I can shoot, and the shots will count. If you get hit once on the enemys side, you must sit down and go back to your half, and drop the flag where every you got hit. There is no throwing the flag. (depending on how you are playing) So it is pretty much a take all or die trying. If you are playing with a hit limit, and you are hit on their side, it counts twords one hit to you death. If you are just playing where you sit down, all that you have to do is return to your side without the flag, and sit down for how ever long you agreed to before the game. I know that all of you have played this classic game, so you know how it goes. Just shoot each other while playing capture the flag!
All for now, I will add more later!