Unreal Engine is an industry grade, robust game engine. While previous engines offered UnrealScript for implementing new behavior, Unreal Engine 4 uses C++ exclusively along with visual programming "Blueprints" that are generate C++.
Pressing and holding ALT while dragging left-click will orbit the focused object, while dragging right-click will zoom in and out of the object.
Geometry brushes have built-in behavior for collision, tessellation, and material tiling. They are used to "block out" an environment and then they are converted to static meshes.
A brush face can be selected by holding CTRL + SHIFT + left-click on a face. All faces can then be selected by going to the Geometry drop-down and selecting Select all adjacent faces.
Objects such as brushes can be duplicated by copy-pasting or by holding ALT while transforming the object.
Physics simulation can be enabled for an object by going to its Physics section of the Details panel and ticking the Simulate Physics checkbox.
The physics of an object can be constrained to specific planes, such as the YZ-plane, by using the Constraints field in the Physics section of the Details panel.
A trigger volume is one that emits an event if an actor collides with it.
Blueprints are compiled into generated C++.
A reroute node is used to steer paths of blueprint graph edges.
Macros are mainly used to group simple, frequently used instructions. Unlike functions, macros are inlined.
A variable is created for each component included in a blueprint which points to that component.
Event dispatchers allow the binding of one event to another.
The Spawn Actor From Class node can be used to spawn an actor of a specified class. One can specify the transform to use upon spawning, how it should handle collision when spawning within another object, and a reference to an instigator: a pawn responsible for damage caused by the spawned actor.