"My process is about iteration, which sometimes means stepping back to planning stages. [...] Sometimes I spend an hour iterating on an area and it clicks. Other times I spend that same hour, and eh, maybe best to set it aside and try something else. [...] How do I tell? There's a gut feeling from experience building similar levels in the past. There are also a bunch of heuristics and patterns to check against. Does the player know the goal? Can they anticipate a solution and plan for it?"
In this particular scenario the trick was that the player could go through the lasers and trigger an alarm but he could also:
- Disable the lasers when the guard was patrolling away from them and then go into the red zone and silently take the AI down.
- Use the Camera attached to the walls to scout the location by traveling from camera angle to camera angle. At this point in the game this is an already well established way of scouting interior locations.
- Use the drone to explore the hallway and incapacitate guards.The corridor beyond also has a bunch of strategically placed junction boxes that can be hacked to incapacitate to incapacitate two guards at the same time.
"After the initial design discussions, maps were sketched out by the design group, and then built by the level designers. Once the initial version was complete, regular playtesting began. Many changes were made throughout the playtesting cycle, often resulting in drastic changes to original plans for the map. [...] [Warpath] was the first TF map in which teams respawned in different locations based upon which control zones their team controlled, and this led to a long test cycle where respawn points were moved many times." -- Robin Walker, from "Half-Life 2: Raising The Bar", pg. 48 (emphasis ours)