Hold click on a flame, drag it where you want to spread the fire, then let go of the click. The goal of the game is to exist as long as you can without going out. Each turn a tree will change states Seed > Sapling > Tree. You can only catch fire on trees. Keep note that the tree that you catch on fire will burn 2 turns after it sets on fire. Fire can not survive without fuel. You also will lose the game if you have 15 or lower points. Every time a flame catches on a tree, you will get 1-10 points for it. Each move you make costs points. The starting 2 flames you get will burn out on round 2 if they aren't spread out on a tree.
Please read the instructions for detail. Hit 'G' to give up if you have no more fire left. And please, don't restart the game immediately after you have no fire, the high score won't be set if you don't get the game over screen!