gaming odds algo with house edge

I am looking for an algorithm for a gaming gambling online mobile app. This algorithm should help to calculate the odds of each game in order to ensure that the house edge is set at an acceptable level. I do not have a specific house edge percentage in mind, so I am open to any suggestion that will help keep the app balanced and fun for all users. The algorithm should be used on both a mobile app and website. i would like it in js and also shape it so i would profit form it in the long term