Every map has to be about something. There has to be a goal, a reward for pressing buttons, shooting enemies, solving puzzles. At least that's how I feel: I want to feel like I've achieved something beyond the sum of the tasks the map gives me. I've been trying to formulate some goal or other for a map I've been planning, and that's really been the hard part.
A campaign map doesn't have that problem. There's an overarching story to guide me, the goal is "make it through the level to the next plot bit". There's voice acting and cinematics to reward me, Alyx talking to her father, Kleiner broadcasting to the city, etc., all leading to the game's climax. But in a self-contained map, I have to provide the goal. I have to tell the player "this is what you're working towards".
My idea was, okay, there's a Combine installation that needs to be shut down or destroyed. That's easy enough. That's a common goal.
What kind of Combine installation, though? What does it do?
After all my puzzles and combat encounters, the player is gonna barge into that Combine installation and blow it up or flick the off switch or whatever. The actual act will be just as basic as the rest of the map: press a button. So that act of pressing the button needs to have meaning. What did I achieve when I blew up that Combine fortress?
Will this allow the rebels to mount some large offensive? Was it producing weapons? Churning out troops? Jamming communications? Conducting horrible experiments? Housed a superweapon that could obliterate entire city blocks?
And I have to make that decision before I start building it, because its purpose will inform its design. Form follows function. A secret lab full of torture chambers will have a different design than a weapons manufacturing plant or a troop garrison. So I can't just build a generic outpost and pencil in its purpose later, not without major, major revisions that may as well be a complete rebuild.
And coming up with that sort of purpose or goal is hard, harder the more I want the narrative to make sense. The map I'm planning is set in an urban environment that's largely accessible to regular citizens, so any sort of super secret, super access restricted installation is out. I've written myself into a corner before I've laid down the first brush.
Writing it all out like this helps me focus, so that's nice, but the problem doesn't fully go away.
(This is the next logical step after
last week's journal about planning.)
The planning phase is where you draft the overall play through steps, think up a theme and the kinds of engagements you want the player to have. The block out phase is where you work on a very basic layout with some mock up encounters throughout and can easily make changes if something doesn't work the way you intended.
Neither of these phases are "easy," but they are when the map is at its most adaptable.
As for your current theme, the combine facility in an urban environment accessible to citizens, that certainly wouldn't be a secret. What it would be however, is fortified. The United Nations building in New York isn't a secret, but it's not exactly inviting people in either. There could be a secret entrance though.