After downloading the .zip file, you need to unzip it. You should already have the software to do so. If not, you can download 7-zip. After unzipping the contents of the .zip file, you will find a survival.jar file inside. If you already have java installed ( www.java.com ), you should be able to double click it if you're using Windows OS and the game should start. If it doesn't you might want to check if your video drivers are up to date. To start the game on other OS, you should try googling on how to run .jar file on your specific operating system.