So the game is finished, but length of game? 2 hours or 20 hours?
Length of visual novels is fairly dependent on how you play them. If you hold skip the entire time, you'll get to the end in about 2 minutes. If you take 5 seconds to read each dialogue box, it's probably between 2 and 3 hours.
If you stop to "inspect" certain images/animations, that will obviously add more time as well.