The levels are tricky, and complex. Seeming to take up little or no space, while feeling large, like your only seeing a tiny part of any area you are confined in. While in the city, you know that just over that next rooftop is another street, and a city beyond that. The levels in Heretic II feel real. Much of this comes from the level of detail.
Houses have tables, and tables have chairs.
On the tables are books or plates, and paintings adorn the walls. Texture work is beautiful with textures of Unreal quality, and the levels are interactive. In one spot, you have to hit a switch to smash a crate into a door. This leaves a tiny hole that you cannot jump or climb through and left me scratching my head. On impulse, I hit the switch again, watching the crate smash another third of the door away, and again until the door was completely gone.