If you type in any number before 1000000 as the game ID, a game will start to load but doesnt completely. An automated message comes up saying "The requested game does not exist. It may have been deleted by the game creator" before redirecting you to the your games tab. What I take from this is that the first game has the code 1000000 and games have counted up onwards.
Another good start is just Fizzer's profile :) This is his favorite game : https://www.warzone.com/MultiPlayer?GameID=1000045
The about page states 10 000 games per day.