Below is the description of "Challenges" present in the current version of the mod.
"Challenges" are the special conditions present in all scenarios. You can know the name of a challenge by a special label on the scenario photograph, like this:
https://i.imgur.com/esC5Niw.png
When you launch a scenario, you will also get a short description of what challenge are you facing, like this:
https://i.imgur.com/T4rmLmd.jpg
Below are descriptions of all challenges:

• Goodbye, Franko. Franko, the door-to-door trader, has managed to escape the city. You still have Katia who can bargain better than anyone, but without Franko it's her who will be forced to turn into a door-to-door trader instead.
  
• Resilience. After a short break in the beginning, the night attacks on your shelter will become progressively worse with each day - to the point where you will be forced to leave all your survivors on guard. Winter is not coming, but the autumn will be getting chilly.
  
• Protect the child. The father and his child against the world. Stock up well in your first night, because then you better stay home protecting Iskra before somebody else arrives. One raid with only Iskra indoors - and you might loose her.
  
• Pacifism. Your survivors vowed to never attack anyone, with shelter protection being the only exception. They will refuse to equip weapons, and they will hold back to absolutely everyone in a fist fight.
  
• Survival of the fittest. Your group is less affected by moral events. But your neighbors are not particularly happy about your cold-hearted attitude. You won't receive either help or requests from your neighbors (with rare exceptions). It will also affect those who come to join you: you are getting neither kids, nor altruists like Cveta or Zlata - they want nothing to do with you. Outbreak of crime comes within just a few days - better get those holes boarded up.
  
• Eternal winter. The winter will last for the entire war. There will be no locations blocked due to snow, but don't worry, other things will stand on your way. Raiders will visit you less often and won't hit as hard, but don't get too relaxed either. This scenario is "Winter Extreme" in a nutshell. It's ill-advised to pair this challenge with either "Random locations" or "No free loot" modes, as in both cases you will have half of the map blocked due to snow for the whole playthrough.
  
• It's getting colder. Winter starts at the day 1, but the good news is, you get a good combination of skills that will help you to make it through. Pretty much "Winter Lite" scenario.
  
• Why us?. It's pretty much "Our castle", but tougher. You get no decent fighters in your group. This one is longer and even more brutal.
  
• Cold as hell. Once again, it's early winter, but this time your crew is unprepared, to say the least. They can't lift much, and their skills are not helpful at all in those circumstances. And on top of that, you get a child to take care of. "Winter Hard" is what it is.
  
• Slow, but steady. The infamous couple of the least capable survivors in Pogoren. Neither of them can pack a punch, and they can't carry much, which means your development will be very slow. Luckily, they will have a bit more time than every other group until the harsh periods. And yes - they are now actually slow!
  
• Paranoia. The war has taken a heavy toll on your survivors' sanity. They see ambushes everywhere they go. They will refuse to go to the same location twice, at least for a few days. In this challenge there are no locations blocks for winter and fighting. Here your main enemy is your own mind.
  
• Pilgrimage. The good old "Solo Marko" scenario with a twist. You get exactly zero resources in your shelter; everything you might need must be found outside. Marko will be on his own until the ceasefire. With "illegal stashes" exploit removed... This might just be the most brutal challenge of them all.
  
• Tight bond. Two survivors is all you get in this scenario. They rely on each other deeply; if one dies, another will take their own life, and it's a game over. There will be no new dwellers.
  
• Our castle. You only have a few days until the outbreak of crime. At least you get Arica, who's a decent fighter. Still, try to reinforce your shelter ASAP.
  
• Back to basics. In this challenge there are no electric parts in the whole Pogoren. You are left with only the most basic fittings. It's late autumn. The long, suffocating winter is soon to come, after which you have to be prepared for frequent and violent attacks on your shelter.