The graphics in my vulkan based engine is finally starting to look like something..
Procedural landscape with heightmap for physics, trenchbroom map parsing (building) - with automatic physics.
All setup of logic (doors, teleporters, enemies, player etc is set up and defined in trenchbroom).
The engine knows what to do when it loads the map. So trenchbroom is your editor.

Enemies that wander around (capsules \ robots). They shoot if you get close.

Player character controller with wasd movement / shooting and all that.
Ladder system, doors with triggers.
point lights, sun light, shadows.
Teleporters.
Irradiance field for light baking.