A few reasons.

One, while there are several guides on basic game mechanics, there do not appear to be any that tell you what you should be doing to win.

Two, this game can feel extremely unfair when played incorrectly, yet relatively straightforward when played correctly.

Three, I like making guides.

Simply put, you don't have time to screw around. In the first 2 zones, the generators and furnaces will be powered, and (b)locked doors and broken appliances will be scarce or non-existent. You will be able to satisfy your explorers needs by typical methods (waiting inside buildings to warm up, sleeping on beds to restore energy, cooking food in relative comfort) As you progress, the amount of obstacles in your path will increase, drastically increasing the amount of time you must take to accomplish these same actions (generators and furnaces must be repaired and refueled, doors must be unlocked or unblocked, windows and doors must be repaired to stabilize temperature, ovens must be repaired to cook food, and searching buildings in the dark will be slow going).

What does this mean for you? It means you should be taking your time while you can, and sparing no cost to progress when you can't.

In the first two zones, you should be gathering as many supplies as possible without wasting any time. Your priorities are food, and tools. If you find a kitchen, or utility room, loot every container. If you find a crowbar or lockpick, save it. DO NOT use them in the first 2 zones. Use the key ring. The temperatures should be mild enough that standing in the cold for a bit will not pose a concern. If you find an axe or a hacksaw, gather as much wood as you can in the first 2 zones (you will likely not need more than 10 - 15 planks, depending on how poor your luck is). You won't have time later. If you find food, cook it all. You will need it. Lower priority containers to search are end tables in common rooms, as they can contain several somewhat valuable items, including candy, bullets, and most importantly, energy bars. Make sure you are topping up your energy with beds, but take care to not sleep so much that an anomaly appears. If it does, it is not the end of the world, but by sleeping moderation you can avoid them entirely. Once you've looted all the important items and unlocked the exit, exit the zone and move onto the next.

In the last 3 zones, the game's difficulty begins to rear its ugly head. Doors are locked or broken, generators and furnaces are cold and broken, anomalies become more deadly and the chill winds whip harder with each zone. At this point, looting is secondary, and leaving each zone as quickly as possible becomes your objective. Simply put, any efforts to spend time looting or searching buildings for more items will not be worth the time invested. Any effort to maintain your explorers will be ineffective. You should be laser - focusing on your objective: find the gate, open the gate, enter the gate. Do not waste time trying to conserve resources. If a door is locked, use a crow bar or a lockpick. If the building you entered is unrelated to your objective, leave it and enter a different one. If your explorer is tired, feed them coffee or an energy bar. If your explorer is hungry, wait until they are both hungry and cold, then feed them some warm food. If their condition is not immediately life-threatening, let them languish before tending to them.

Your explorers are more hardy than they may appear: even if their needs are empty, they will not fall until their health reaches zero. Additionally, many items that restore their needs also restore health. In the same vein, items that restore health can be considered the same as items that restore needs, as both accomplish the same goal - keeping your survivors on their feet. For example, if your explorer is hungry, and you have rotten food and some pills, go ahead and feed them the food. Their hunger will be restored, and should they happen to become ill, let them suffer for a bit before feeding them pills. Assuming you tend to them in a reasonable time frame, the pills will have completely counteracted any health drain from the food poisoning. If a survivor is suffering from the cold, which is cured by a medkit, allow it to bring them to death's door before curing them. The medkit will greatly restore their health, increasing their effective lifespan greatly.

Playing in this way, you should begin to see improvement. If you do not, do not be disheartened. This game, while not aggressively unfair, does contain some elements of luck to it. After all, there is no way to predict what items you will get, what objectives you will have, or what doors will be locked. What I have outlined here is what I consider to be the best strategy for this game, but it is not the only one. If you read this, and happen to have any questions, post them in the comments and I will answer them, should I see them.