So i'm sure this isn't completely original but I just wanted to share what I think would be an awesome concept for a battle-royale style game. I'm imagining a mix of Rainbow Six Siege, PubG, the Shanghai map from Battlefield 4 (General building style), and the hospital finale from Left 4 Dead (Extraction).
The core concept would be scaling a skyscraper (maybe 50-80 stories?). Everyone spawns on the ground floor, with a goal to get to the roof for extraction. There would be multiple routes up the building, elevator shafts, stairwells, window washer lifts, vents, etc. The tower would also include a variety of locales, some floors might be largely cubicles, while others might have multiple levels and balconies for sniping.
A fire would slowly move up the building as time progresses, the only way of knowing your floor is about to catch fire is through in game fire alarms. The fire would start slowly (maybe in the basement?), but as the round progresses would begin to grow. At the start of the game should you choose to go to the basement you might find better loot, but risk being killed by other players, or getting caught in the fire.
On each floor there would be a randomly placed breaker box, that would allow you to cut the power to the floor for a little while (The box would be random each time, to encourage exploration). Cutting the power would stop any elevator from moving beyond that floor, and would also disable the fire alarm in addition to cutting off the lights (emergency lighting would be employed so you could at least see).
Higher level loot would generally be distributed higher up in the building. There would be no guns on the ground floor to prevent a complete chaos. The basement would have more significant loot than what you would typically find on the first few floors.
The goal is to reach the roof for extraction. There would be multiple ways of reaching the roof to ensure camping is kept to a (relative) minimum. You also won't find any additional ammo or healing items on the roof or top-most floors. The extraction won't show up immediately, therefore everyone wouldn't simply sprint upstairs.
So those are just some thoughts I put together, and I figured I'd share.