This Game is meant for Boy Scouts.

paper and pencil for each patrol

Need an open field up to 200 yards long, depending on patrol sizes.
Create a simple code for numbers equalling letters, such as the example below. One leader is the Code Keeper.

Create coded messages – one for each patrol, but all should have about the same number of letters. Possibly easier for younger patrols, such as duplicated letters or slightly shorter messages.

All patrol leaders gather with the game leader at one spot. 20 yards away stands another scout of each patrol. 20 yards further stands another scout. And so on for as many scouts are in the largest patrol. The last scout in each patrol needs a paper and pencil. 20 yards past this last scout stands the Code Keeper with the simple code.

To start the game, each patrol leader is given his patrol's coded message. As soon as he gets the message, his teammate 20 yards away runs to him. The patrol leader tells him as many of the numbers as he wants.
The scout runs back to his starting point while the next in line runs to meet him. He relays the numbers then returns to the patrol leader for more numbers.
The 2nd scout relays to the 3rd and so on until the last scout gets the numbers. He runs to the Code Keeper and tells each number. For each number, the Code Keeper tells him the corresponding letter which he writes down.

When the patrol has all the numbers transferred and decoded, the entire patrol gathers at the patrol leader and yells out the message in unison.

Patrols with fewer scouts have less chance to mis-translate, but the last scout must run further.
Patrols may try to memorize many numbers or do them one at a time to be safe.

An example message (each scout would run a little over 1/3 mile)
17, 21, 17, 10, 7, 7, 6, 21, 8, 13, 21, 8, 3, 13, 21, 19
W E W I L L B E P R E P A R E D

An example Code:
A – 3
B – 6
C – 9
D – 19
E – 21
F – 22
G – 14
H – 1
I – 10
J – 23
K – 4
L – 7
M – 11
N – 2
O – 5
P – 8
Q – 12
R – 13
S – 25
T – 18
U – 15
V – 16
W – 17
X – 20
Y – 26
Z – 24