I suggested this in the past on the DLCs thread, and I supposedly had to wait a few days before posting my own thread (that, or everyone had to wait). Regardless, I figured that I should make my post an actual post now, giving it a better chance to be seen by Techland, with the hopes that at least one of these make it in or more.
1. Survival Mode. It's more of an extra difficulty. Similar to Fallout 4's survival mode, you now have to eat, drink and sleep to survive. You can scavenge for food and water throughout the world, sleep in a bed at a zone to replenish your strength. You now also have to thoroughly look for air drops, as they contain Antizin. With this mode, you now have to use Antizin yourself. If you don't, the infection will take over and kill you.
2. Sandbox Mode. Separate from Story Mode, when you start a new game in Sandbox Mode, there is no main story. You jump right into the world in a random location every time, and explore to survive. This would work hand in hand with Survival too.
3. Night Mode. Similar to I Am Legend, the world is empty during the day. Zombies are nowhere to be seen on the streets, except for inside dark interiors. Interior cells will always have zombies in them unless cleared out. At night, zombies will flood into the streets.
4. Hunted Mode. Zombies always know where you are, no matter what, and will hunt you down wherever you are. If you are in Old Town near the plaza, where all those zombies are, it doesn't matter if you're on top of a pole or building; they'll shamble straight towards you and extend their arms out to reach for you. They always see you, and you'll always be hunted.
5. Virals-Only Mode. All zombies, walkers and specials, are replaced with virals, that now populate Harran.. Perhaps three difficulties for this so it's not impossible. The streets look empty of Walkers or Specials, and Virals will occasionally roam about. Fire a gun, as in vanilla, and they will come. If you've watched 28 Days Later, think of it like that. As for difficulties, it's more of how many virals appear on the streets when you aren't firing a gun. It could be as few as three, or as many as thirty all about. Either way, you'll want to be on the run more often.
6. Loner Mode. All safe zones from Story Mode are overrun by the infected or turned from lack of treatment. No place for anybody. It's your job to take them back, one by one. Places like Brecken's Tower and Lena's Tower will be overrun by the infected, and now you have to reclaim them.
8. Special Mode. There are no Walkers or Virals. Only the special infected rule the streets of Harran, day and night.
9. Settlement mode. While the settlements of Dying Light don't need your help, it's nice to make your own settlement on the go. Or rather, for this game, a safe-house. In case you're too far from any safe-house, you could craft your own in the building you're standing in, but only if zombies can't just walk through the door. You can craft barricades, UV lights, and a sleeping bag for you to rest your pretty little head. You can choose to keep it as an official safe-house, or dismantle it in the morning. I mean, it's technically a mode, so I guess it fits here?
10. Growing Horde Mode. Not the actual name, but here's the idea. With each day passes, more zombies spawn across the map. After several days, zombies will dominate the streets, forcing you to stick to rooftops and avoid the streets. Similar concept can apply to The Following, in towns and villages.
11. Be The Zombie single player. You can play as a viral or a Volatile and hunt survivors.
And I don't know if this is okay, but I have a couple of feature requests:
1. More open interiors. If the game can handle them, I'd like to see more places be enterable; more houses and buildings that are part of the exterior cell. More places to hide, more places to explore. I love exploring.
2. Infection. As Kyle Crane, you're infected from the start, bitten by a zombie upon touching down in Harran. In the case Techland (or you, if you (Techland) is reading this) adds in something like a Sandbox mode where you aren't Kyle Crane, you should carry the risk of catching the infection. If you get infected, you'll need Antizin. Of course, this feature would apply to the above Survival Mode.
3. Shooting gun spawns horde of walkers. In the current game, shooting a gun draws nearby walkers and spawns virals in the distance. This feature would have a gunshot spawn a large walker horde that reaches your location.
4. Zombies wander more. I feel like the zombies should wander more, as they're trying to search out survivors. While some could just stand still as they already do, I feel like the majority of the zombies should be wandering around.
5. Permadeath for sandbox mode. Option to choose before you start. If you die, that's it. You have to start again.
6. Random horde spawns. I guess this would be more of a feature than a mode. Basically, it allows large hordes of zombies to randomly roam around the map dynamically. So if you're in the middle of a field in The Following and you're looking through supplies, a horde can randomly appear in the distance and shamble through, taking you completely by surprise.
7. Resurrection. This would fit probably in modes like Nightmare Mode, Survival Mode, and Sandbox Mode with Nightmare Difficulty. Anyone who dies turns into a zombie. Rais' men who are killed by Virals, they come back. That fisher in front of Brecken's tower, when he dies on the mission, he comes back (even though he'll reappear again later).
8. Dependence on Air Drops (Sandbox/Nightmare/Survival Mode). It always bothered me in that the original game, while air drops occur, they don't have too too much of an effect on the safe zones. Sure, you bring them to the quartermaster and all, but it feels less like they're making a difference. It would be interesting if, for certain modes, safe zones now become dependent on air drops, especially if they contain Antizin. These would only apply in modes outside of Story Mode. If air drops are not delivered to main safe zones after a certain period of time (these would be missions spawned for you), that safe zone now runs the risk of becoming overrun as people turn. If a whole safe zone turns, it is lost, and you are granted a mission of reclaiming it for survivors.
9. Finite resources. The majority of Harran is abundant with supplies to collect and scavenge. With this optional selection, all resources are finite, meaning when you collect them, they don't respawn after a few days, meaning after a while, the only supplies you will find will be from air drops and enemies scattered around the map, as well as whatever you may find on the infected or corpses of enemies like Rais' men or bandits. Areas where bandits and Rais' men spawn will always respawn with supplies, but areas elsewhere across Harran will run out of supplies.
10. All zombies turn viral at night. This is for hard or maybe nightmare. Basically, at night, all zombies become virals and chase you. Gives you a real reason to go home at sundown.
11. Only Volatiles come out at night. This is connected to the suggested Night Mode above. At night, no zombies except Volatiles will come out and hunt.
And one thing I'd like to add about survival mode. Perhaps it'd be possible to collect food and water as objects, depending on what they are, rather than eating or drinking them on the spot? I believe I Am Legion (mod) did that.
I'm glad Dying Light is still being worked on and improved long after its release. Personally, I feel like these modes can give it so much more life than it already has. I would more than love to start a sandbox survival playthrough and just survive as much as I can and as long as I can, perhaps while running from virals in a viral-only Harran, or avoiding the streets because the special infected now rule the roads.
There are so many possibilities, and I believe Techland can follow through on them!