Don't Starve is a survival game where you spawn in a new world every time and you need to gather materials, fight creatures and craft new things in order to progress through the various technologies and magics, all in the name of not being killed and not dying of starvation. Depending of how the world starts, you might be able to quickly get gold and get right along with the science machine - or you might be stuck between tombstones and spiders and die.
This scenario happened to me the first time I've played, I looked forever for precious gold and couldn't find any. As such, the game is a bit at the whims of it's random number generator. A bit like Minecraft or Terraria, but these two games are more focused about exploration and making structures than about pure survival. Your health isn't a big issue in most games of that kind, in DS, it is, it goes down constantly, alongside that brain icon thing, but I'm not even sure what that was. You also have health, but it's not a problem besides if you try to attack enemies, I attacked the first thing I saw, and it was a huge bird, and I died in two hits tops. Maybe it'd be cool to see more stats exposed like your attack, defense, how many hit points enemies have, etc.
The feeling of exploration is great because you don't know what you'll find. Weird altars that bring you back to life, holes with scary enemies, weird crab creatures, buffalo-like monsters, king pigs, the list goes on. The game can get legitimately scary at times, these spiders are very creepy and I chose to get out of a hole I crawled in rather than stepping forward in the darkness. Light is important in DS, light sources such as torches and campfires are easy to craft and you can make safe fires that can get more fuel as the days go by. It's impossible to do anything in the dark anyways, you need a torch with you - and even then you'll be struck by cold if you go too far from your camp. Speaking of which, I find weird that you can sleep on a bedroll to make night pass faster but in return, it drains your food levels so much.
You unlock new characters by surviving as long as you can or by finding them in the environment and they all have special abilities, strengths and weaknesses and that's all good. That being said, I never got very far with my character, I always tried to explore too far or ate all the available food, or decided to poke a giant pig with my axe, so I haven't see much of these other characters. The progression is also difficult to figure out simply by looking at the available recipes because you spend a bunch of time gathering twigs and rocks and making more pickaxes and axes to gather more logs and rocks and other minerals, it's not like in other games of that general genre where you easily see wood->rocks->iron->gold->diamonds, or something.
In any case, I spent a good time with Don't Starve and I only starved once, it's more a survival game than a building game - I wish you could make yourself a nice little wood house or something to put your things in - and you only have the minimum amount of information that you could use, but you still carry along, picking up things to make other things, upgrading to traps, catching rabbits, deciding to steal an egg and regretting it dearly, then you get close to making a hat but you get too greedy and a huge spider eats you. As I see it, DS might be more of a game where you remember specific moments and wish to retell them later on than other of it's genre, maybe it's because of the setting or the style, maybe it's because things can go crazy really fast.