How long is Dying Light 2: Stay Human? The new open world zombie parkour game from Techland features a massive city made of multiple districts, a lengthy main storyline and dozens of side-quests, plus random encounters, parkour challenges, boss fights, scavenging, and more.
How long it takes to play isn't going to be the same for anyone, and in a game like this it's hard to even define finishing, but let's at least try to ballpark it anyway.
I've now spent 61 hours in Dying Light 2. I reached the end of the main storyline in exactly 50 hours and saw one of what I presume are several different endings before the credits rolled. Those 50 hours weren't all spent doing main story quests—I also completed a dozen side-quests of varying lengths, spent time exploring, scavenging, crafting, took part in radiant rumbles and random encounters, did a few parkour challenges, and more.
I'd say I spent roughly 25 hours of my playtime specifically on main story quests, give or take. One thing to keep in mind—running straight through the main story and neglecting everything else might be difficult. City districts have different ranks, the lowest being rank 1-2 and the highest of 5-6. Earning combat and parkour XP raises your rank. You can go into a rank 5-6 district even if your own rank isn't that high, but you'll find the enemies there much tougher than you will in a district that is equal or lower to your rank. So, if you primarily follow the story quests you may wind up feeling overmatched as you get closer to the end.
Again, playtime is going to vary not just on what you decide to do but how good you are at doing it. A co-op partner who was also reviewing the game said they'd reached the ending of the main storyline after 40 hours of play, 10 hours earlier than I did. They were also rank 7 whereas I was still a few ticks below rank 6 at the time.
As far as the vaunted 500 hours Techland said are needed to completely 100% Dying Light 2, I'm not sure. I'm at 61 hours played and I still have loads of sidequests to complete, challenges to beat, collectibles to find, and there are even areas of the city I haven't spent much time in. I really can't say if it'll take anyone quite as long as 500 hours to complete everything, but Dying Light 2 is a big game and it feels within the realm of possibility.