The game activity is based on moon position.You can find these charts on various websites.I have been unable to find a website I like enough to use so I buy a booklet for $24 and it has the whole year in it so I can plan my hunting days off.The chart seams to work better for deer than walleye and at times the activity, or lack off it, does not seam to correspond to the published activity predicted.But other times it corresponds with a better bite or good deer movement.Just another tool to help you be a more productive sportsman.