Originally Posted by ichtyander  
Here's a bit of info I sorted up in hopes of making some things a bit clearer. It's all gathered from actual info from interviews, trailers etc.
 
What is No Man's Sky?
- In a nutshell, the goal is to earn money, get the best gear and survive the trip to the center of the galaxy. Yes, you can explore planets or stay in one forever, but if you're asking for a goal, a purpose, that's it.
 
Why would I want to get to the center of the galaxy?
- It's the main goal of the game, the only objective. Apparently, there will be "a compelling reason to head towards the center of the galaxy, as well as an ending that will provide you with a sense of closure. But there will be a reason to continue playing after that ending". Remember that Minecraft, Don't Starve, DayZ or even Dark Souls don't have a clear goal, they throw you into the world without telling you what to do next. 90% of Dark Souls is melee combat and walking, sounds pretty boring if you think about it that way, doesn't it.
 
What are the main incentives? Why would I want to play this game?
- As was mentioned, leveling yourself by ways of earning money and gear while trying to survive in a harsh environment is the main incentive, like in a vast number of games, or at least it's the main gameplay mechanic pushing you forward. The other incentive is of course pure exploration, which is enough for a lot of people but technically it might not be. You engage in a number of activities, both on the surface and in space, earn money, improve and buy gear and reach the center of the galaxy. Of course, getting money will be challenging, it will often put you in dangerous situations and you will probably die a lot.
 
So what do I do, what activities are there?
All of these activities earn you money, some more than others:
 
Non-violent:
- Exploration (discovering and naming of creatures, plants, locations, crashed ships, structures, artifacts, portals to dangerous planets)
- Resource Gathering (gather and sell minerals from a fictitious periodic table of elements using a multi-tool for scanning, a mining laser for gathering)
- Trading (buy resources cheap from one space station, sell them to another for profit)
 
Violent:
- Destroy Guardian Robots (gathering and killing too much alerts robots that hunt you down, you have weapons and grenades at your disposal)
- Escort and Defend (escort ships on their journey, defend them from enemy attacks)
- Destroy Ships (destroy trader ships, lone or groups of traveler NPCs, choose sides in huge fleet battles or evade them altogether, kill the local police)
 
There is also one "core thing" you can do for every solar system, and this "thing" is of great significance, fundamentally changes that solar system and players can choose whether or not they want to do that.
 
*Note: They've mentioned that killing creatures doesn't actually earn you money (discovering and scanning them does), but you can do it nevertheless.
 
How does exploration actually work?
- You have a galactic map with all of the stars revealed. Clicking on a star shows its basic solar system data, with more info if someone's already been there and shared it. You hyperjump to the selected solar system and then target one of the planets. As you enter the orbit, your ship's computer scans the surface and shows you essentially question marks, points of interest detected on the surface. These points of interest can be any of the aforementioned activities that earn you money while on the surface as well as trading posts, portals etc. Basically, you get rewarded for revealing what the question marks are and then do the stuff related to said activity, whether it is scanning of new species, mining resources, a dangerous trap, jump to new worlds, kill some robots etc. You can freely explore the entire planet if you want, and you'll probably find some nice things out there as well, but a few of the key locations will be marked with these "question marks".
 
Just imagine Far Cry 4, but instead of the towers revealing icons and those icons depicting exactly what the missions are, you reveal icons just by arriving at the planet and discover what the icons are by actually going there.
 
What do I do with all this cash I earned?
- Well, the main goal is to survive the trip to the center of the galaxy, so you want to make sure you can actually pull this off. There are three main things you can upgrade:
- Suit - (shields, carrying capacity, jetpack, degree of survival in toxic, corrosive, radioactive, acid and other environments)
- Weapons - (improve scanning range and type, resource gathering, laser beam, plasma grenade, energy shot, for space there are different weapons with different specialties like lasers for shields, plasma for hull damage, torpedoes for heavy damage but with slow projectiles)
- Ship - (buy new ones actually, but they can have different stats defined into three classes: Fighter, Trader and Explorer, different engines, stealth tech, different types of weapons for different occasions)
 
Doesn't sound all that difficult. What are the obstacles, where's the difficulty?
- If your ship is destroyed, you respawn after death without your ship and cargo but you still have your hard earned money and suit upgrades. If you get killed while on foot, naturally you loose what resources you had on you and respawn near your ship, still having your money and suit upgrades.
- Planets have different atmospheres, radiation, toxic and corrosive environments, liquid hazards like acids and alcohols so you need to upgrade both your suit and ship to survive in these harsh environments.
- Some planets have robot guardians that attack you if you exploit (as you should) the planet's natural resources, kill off wildlife etc. In other words, the robots punish you for doing everything you can to survive and improve your gear.
- Participating in conflict between factions will win favors with one over the other, meaning one faction will give you wingmen for support or trader discounts while the other will actively attack you if you're in bad relations with them.
- Attacking outposts and space stations enrages the local police. You don't get rewarded for attacking space stations but you do for killing cops (or any ships for that matter).
- Fuel is used for interstellar (hyperspace) travel and is very expensive. An easier way of getting fuel is by mining for resources, or you could do any of the other activities to earn cash and spend it on fuel. Fuel also takes up cargo space so you need to balance that if you want to do trade runs.
- Hazardous planets (or maybe all of them?) deplete your suit's oxygen levels so you need to be mindful of this when embarking on longer journeys through the inhospitable terrain.
- Portals to other planets can be extremely dangerous (you can only use them on foot) but can also give larger rewards, since you're basically warping to a high level area while you're still at a very lower level. Also, each portal requires a different weapon or combination of weapons to activate.
 
So will all of this actually be fun or worth it?
- Well that depends, it might get boring quickly or the variety of combinations might keep things fresh at least for a few dozen hours. People play Destiny, Far Cry 4, Dark Souls or Don't Starve, games which have extremely repetitive and annoying elements for a lot of people but are still loved by a great many people. My point is, No Man's Sky clearly has gameplay, and while exploration is directly encouraged and essential, it's not the only thing you can do in the game. It's not a walking simulator by any stretch. You earn money, have a goal you can pursue, upgrade your gear, engage in combat, have a lot of dangerous situations etc. That being said, it might turn out to be a boring game, it depends on balance, how interesting the activities are and a number of factors, one of which is the player himself. It's not a game for everyone, but those are rare anyway.
 
I hope this clears some things to some people, especially with posts saying there is no gameplay and such. Also, I recommend reading the NMS wiki archive on reddit that has all of this info and more.
Guys, man. The trailer DOES showcase the mechanics.
 
Here is exactly how it works
 
● You start on a random planet. Planet may be tough, may be easy. It's procedural.
● 90% of the planets are barren of life, emulating our actual universe. 10% will have life/civilization/story elements/etc.
● But every planet, no matter how barren of life, has resources for you to gather. You need these resources to continue your journey deeper into toward the center of the galaxy. Fuel, ship parts, cargo to sell, etc.
● The more resources you gather, the more you screw with the ecosystem, the more you gain the attention of a mysterious 'robot' protector that is meant to keep the balance in the universe and prevent destruction of ecosystems.
● The longer you harvest a planet, the tougher the robot guards they send at you - there are bipedal ones and ones that walk on four legs, but there's a multitude of different types.
● The goal of the game is to get to the center of the galaxy. Something mysterious is going on there, and you're trying to find out what it is. The closer you get to the center, the tougher the game gets - more enemy fleets, more enemies in space, more enemies on planets. Tougher evolved life.
● Each solar system has space stations you can go to. The bigger the solar system, the bigger the space station. Bigger the space station, the better equipment you can get there. You can follow any ship you see in space back to their space station of origin and buy the ship, for example.
● But you also can buy a host of other items that speed up resource gathering, ability to deal with enemies, ship upgrades, etc.
● There are portals - like you saw in the trailer - that once entered, will put you into a completely different part of the universe. What will be on the other hand is a complete mystery, but some will lead to great secrets.
● The narrative is there, but the game is made so that you never have to actually follow it if you don't like. It CAN be a 'walking simulator', it CAN be a game where you gather resources or make a planet your home base. But the goal is, and it takes 40-100 hours approximately to do it, is to find out what's going on in the center of the universe.
● There is a messaging service that you can use to talk to other players, but it's very possible you can pass another player and never even realize it's a real person. How social you want to get is up to you.