Usually there is a simple reason:
- It was just added. A game's first numbers arrive within a day, and its trends fill in over the first week.
- It has not launched. Player counts start on launch day. Before that, there is nobody to count.
- Nobody has reviewed it yet. Reviews show up as soon as players leave them.
- It is not on the store right now. If a game is hidden or removed from Steam, its numbers stop moving.
- Nobody tracks it. Games that members follow are refreshed first. Others get their turn less often.
The games you track and their rivals get fresh numbers every day.
Tip: if a game you track still shows nothing after a couple of days, contact us with its name and we will take a look.