Can someone help me find this movie? SOLVED!

Years ago I was ill in bed and couldn't sleep so I had the TV on. I was blacking in and out so I only vaguely remember bits and pieces but for some reason it's been stuck in my head for the last two decades. I think it was a late 90's/early 2000's movie (which is about the time I saw it IIRC) and I want to say it had the word "Game" in the title but I'm not sure.
The plot as best I can remember was about an underground kind of riddle or clue game, where people followed a blue line or markings drawn around the city that lead them to the next puzzle, and some kind of truth or knowledge that made you commit suicide was revealed to anyone who completed the game.
Sorry I know this isn't much to go on but it's been driving me crazy. Any help would be appreciated.