After the Valley, have a guaranteed special level “The Gates of Hell”. This level design is very clear: “This is hell. These are the gates, and they are closed. You are not wanted here. Go away or perish.” The level is a large cavern, with a massive arc-like fortification across either the left or right side. The gates are implemented with both iron doors and a drawbridge across lava. There is quite a lot of lava, and a lot of demons inside and outside the fortification.