A little late, but anyhow. In my definition of a game engine the ability to load multiple levels without to run multiple EXEs is very significant.
Not every EXE with multiple levels is a game engine. Especially beginners write games with multiple levels this way:
Repeat
...
Until level 1 complete
Repeat
...
Until Level 2 complete
Repeat
...
Until Level 3 complete
But infact this way people write a game for every level. Although this gives you ultimate flexibility, it's also a lot of work.
In a true game engine you are writing the game parts only once and then reuse it with various scenarios for every level. A game engine also contains level editors, or at least a documented level file structure.
Things like doors, codelocks or puzzles are things you don't want to program again and again. It's much easier to tell the level editor "add a codelock to this door, password so and so".
So the use of a level file makes a game engine. For example there are mesh file paths, position, rotation, scale data of them, including command codes for special functions (eg. to make something an interactive door etc.) and other parameters that could be used with the object. But not only meshes are defined this way. Positioning 3D sounds is about the same. Usually for a sound there is a dummy mesh displayed in the editor, that allows to position the sound visually, be it wind, water etc.
NPCs are a further important part. Whether they use a simple algorythm by following some predefined ways, or they use sophisticated AI and path finding algos, that's rather a question of complexity and available time and programming skills.
Today commercial FPS game engines became extremly complex, it's almost impossible for one man to write something like the latest Doom/Quake or Unreal engines. But even a simple, small FPS engine that is useing DX7, like Blitz3D does, can be fun.
In the real world you'll find a lot of game engine projects (besides the big ones). Don't be too impressed by lists of tech features as long as there ain't no playable (and I really mean PLAYABLE, not only a walktrough thing) Demo around - most projects are only 50% or less finished/ready.
As far as I know all popular FPS games used a game engine. But the level designers still need to be very creative and use a game engines possibilities to (and often beyond) it's limits.
Not every EXE with multiple levels is a game engine. Especially beginners write games with multiple levels this way:
Repeat
...
Until level 1 complete
Repeat
...
Until Level 2 complete
Repeat
...
Until Level 3 complete
But infact this way people write a game for every level. Although this gives you ultimate flexibility, it's also a lot of work.
In a true game engine you are writing the game parts only once and then reuse it with various scenarios for every level. A game engine also contains level editors, or at least a documented level file structure.
Things like doors, codelocks or puzzles are things you don't want to program again and again. It's much easier to tell the level editor "add a codelock to this door, password so and so".
So the use of a level file makes a game engine. For example there are mesh file paths, position, rotation, scale data of them, including command codes for special functions (eg. to make something an interactive door etc.) and other parameters that could be used with the object. But not only meshes are defined this way. Positioning 3D sounds is about the same. Usually for a sound there is a dummy mesh displayed in the editor, that allows to position the sound visually, be it wind, water etc.
NPCs are a further important part. Whether they use a simple algorythm by following some predefined ways, or they use sophisticated AI and path finding algos, that's rather a question of complexity and available time and programming skills.
Today commercial FPS game engines became extremly complex, it's almost impossible for one man to write something like the latest Doom/Quake or Unreal engines. But even a simple, small FPS engine that is useing DX7, like Blitz3D does, can be fun.
In the real world you'll find a lot of game engine projects (besides the big ones). Don't be too impressed by lists of tech features as long as there ain't no playable (and I really mean PLAYABLE, not only a walktrough thing) Demo around - most projects are only 50% or less finished/ready.
As far as I know all popular FPS games used a game engine. But the level designers still need to be very creative and use a game engines possibilities to (and often beyond) it's limits.