About 2 years ago, I introduced a friend to X3 - being his first X game he dove straight into an open world/no plot game.
He didn't know about the SETA button (which lets a player fast forward the in-game time), so he used to aim his player-ship at a destination, go downstairs and have his tea, then regularly go back to his computer to make sure he hadn't crashed into a rock / been attacked / missed the jump gate. A delivery mission could last hours instead of minutes.
He played like this for a week.