It was produced in the last 20 years.

It was made in Japan.

One of the main characters was an older guy. There was an eclectic team of characters.

It featured a company that hired people to take part in a confined game, inside a bunker like structure. There were very strict rules in place.

The place was protected by a kind of robotic machine that would routinely patrol the entire complex to make sure they are obeying the curfew. Characters would arrange secret meetings in the middle of the night by avoiding the robot.