I've been working on the railroad
A large grassy or carpeted area is needed. Divide children into two teams. They must build a railroad connection to the "gold mine" in the middle of the area, starting from their side of the room. The children become the tracks. One child lies down with feet and arms extended and together. The next child crawls over the first and with the first child holding his feet, extends the tracks further, etc. However each railroad must have two "curves", a "trestle" (child on elbows and knees), and a "switch back" (three children forming a "Z" in their "track plan" before connecting to the "gold mine". Once the two tracks have joined, then the children "ride the rails" (crawling again over all the "child tracks") to the "gold mine", beginning with the first one down, till everyone has completed the journey. The team to get to the mine first wins.
Choose two couples to start the game. The biggest child in each couple must carry the smallest one. The first couples run from one station to another, trying to get the one letter found at each station. Make it difficult for each couple to get the letter, e.g. hide it at that point, hang it from the ceiling, etc. The couple to reach the end line first with the most letters wins. You can incorporate many kid party ideas to this game. For example, have just one player of each team participate in the relay race, but make it more difficult for them to get the letter from each station. A "buffalo" on the way, or a thief running after each player to steal their letters will add fun to this wild adventure.
Cowboys and Indians
This is a great activity for a western theme party. Choose 2 players to be an Indian and a cowboy. The rest of the players form a circle holding hands up. The Indian moves in and out of the circle trying not to get caught by the cowboy. When the Indian is inside, he can say "close!" and everyone puts their arms down. The Indian is safe then, but when the children forming the circle have counted up to five, they raise their arms again. The cowboy can also say "close!" if it happens that he and the Indian are both inside the circle. He then can catch the Indian more easily, but when kids have counted up to five they can raise their arms again and leave the Indian out!
Foxes and Squirrels
Everyone stands in a circle. Two soft balls represent foxes and a different one is the squirrel. Foxes must be passed hand to hand with the statement "fox". Squirrel is passed hand to hand or tossed across the circle with the statement "squirrel". Balls may be passed either right to left or left to right. The player that gets the "fox" when he is holding the squirrel gets a point. The player with least points at the end of the game is the winner!