Korean tourism is giving free tours for passenger who have four hours lay over or more.if you have four lay over ,you can go out the immigration and there is a booth downstairs with sign Free Korea tour. If you have four hours , Then you can visit a temple in Inchon for free. They have a mini bus that can shuttle you back and forth for free.

I have six hours of lay over and  I was able to visit two places  in Inchon for free after visiting the temples,we went to inchon war memorial then back to airport and you are ready for your flight and make your transit more worthy.