Things You'll Need
Instructions
Lay a bulletin board down flat on the floor. This will be your basic game board which you can decorate however you need to suit the rules of your game.
Open two packs of plastic toy soldiers. You can often get them cheaply at toy shops or dollar stores. Ideally, get two different colors so you can differentiate between teams.
Add several dice. You can either take some from a board game you don't play anymore or you can buy new ones from a game shop.
Take pieces from other games or toys that aren't played with anymore and find a way it could be used in your game. For example, old building blocks or game pieces can be used for weapons for your soldiers, or they can be used to build camps and shelters to protect your soldiers against damage.
Decide how the game is won once you have your materials laid out in front of you. The most obvious way to win is for one side to wipe out all the soldiers on the other team. Decide how soldiers are lost and how a team can get reinforcements.
Devise basic rules for your game which will help you get from the beginning with everything set up, to the end where one team is victorious, either by destroying the other army or with an opponent's surrender. Play both sides as you do this to test the rules and see if an enjoyable battle between the soldiers results.
Tweak your rules and add components to your game board until you have a prototype game you are pleased with. Store the soldiers in two separate bins to keep the teams separate and keep all the other materials together with the board so you don't lose anything.
Write out your rules so someone who has never seen the game before can follow them. Likewise, this will help you keep the rules straight for yourself.
Play your game against another soldier enthusiast and see if you enjoy it. Your opponent may have some ideas for rule tweaks that will make the resulting battles more enjoyable.