Death from Above

Kind of long journey but fun campaign, with some escape events

I took about 1 hour & 20 minutes because I tried to solve the puzzle on map 3 first although I already failed. I'll explain the puzzle later (edit: I can't solve the puzzle, & even this is much harder than RE or Silent Hill puzzles. New record for the hardest puzzle in L4D2 in my opinion, I guess). This campaign is good, but some areas put survivors under pressure, like having a kind of countdown. Bot navigation is fine though. Supplies are good, though in the beginning of map 1, survivors need to walk for awhile to get primary weapons. Directions are good, though some areas are still confusing & need more thorough observation to figure out where to go.
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Map 1 is still a warming up. Survivors only need to follow the paths & do the highlighted objectives. However, there's a bugged place on the river near the ladder leading to the surface. There's a deep area where survivors will get stuck in the water & can't get out unless using noclip. So, just watch your steps near the ladder.
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Map 2 is the introduction of under-pressure events. Survivors mostly go through burning houses. Though there are directional arrows inside the burning houses, the paths are still rather confusing. In my play, I just moved slowly while looking around every few seconds to look for the arrows. There's a place with a gas leak, but I don't know what will happen if the gas pipe gets shot by accident, because in my case, I played safe not to shoot carelessly in the burning houses. The under-pressure event happens near the end of the map. There's a hint to run, & survivors keep yelling, while the fire is chasing behind. I also don't know what will happen if the fire chasing behind hits the survivors, as I also played safe by keeping running after looking back few times.
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Map 3 has an annoying puzzle trap. Survivors are given a time limit like 4 minutes to solve the puzzle. There are 6 buttons including the confirmation button to open the gate. Each button except the confirmation button has a special infected painting on the wall or floor. I failed to figure out so the trap came out: a tank. Even after failing, the button still worked so I tested until I figured out the code. Actually there's a hint about special infected, but players may still be confused, because it's not only about special infected. More exactly, it's about the order of special infected, from the small to big number. However, as far as I know, the order of special infected is random on each play, so literally it's kind of pure luck to solve the puzzle in one play. So, it's better just to camp somewhere safe until the time's out, rather than get frustrated in solving the puzzle, because even the hints come rather late, like when almost 1 minute is wasted, & by the time the last hint appears, you'll only have less than 2 minutes to solve.
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Map 4 is very long journey from the road with many cars to a factory. There are some flying car traps, but there's a warning so they're avoidable. There are also paths that the flying cars can't reach. The main event takes place in front of the called elevator. While waiting the elevator, a tank will come one by one for 2 waves after the normal incoming waves.
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Map 5 is kind of unexpected. Survivors are inside the spaceship!! The objective is simply to open a door leading to escape location, but during waiting the door to open, there's a holdout event. After the door opens, there's the last under-pressure event. The spaceship somehow is about to explode, so survivors need to keep running. The warning pops up again near the end of the map where the escape plane is. There's a tank guarding the escape plane. I don't know what will happen when the time runs out, because in my play I just baited the tank around & then got into the plane with the bots.
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In short, it's a long but playable campaign, with a puzzle & some under-pressure events. Just ignore the puzzle on map 3, ok, & just see it as a normal holdout event. Good to play with bots or friends.