After playing this game for about six months, I feel like this game is going to go somewhere. It's currently in Early Release (alpha) stage, which is why I waited so long to bring it up here.
http://steamcommunity.com/app/244850/It is currently available only on Steam, plans are in the works to release it for the Xbox1 once they get past the Alpha stage. But it is going to require a rework of the networking code because they used Steam Networking, which is proving to be a horrendous nightmare for the PC, and not available at all fort he Xbox.
The "World":
As of December, the World is space, of course. The maximum extent of the world is 6.6 AUs in diameter. For references that is the entire Inner Solar system out to just beyond the asteroid belt. For other references, It would take over 200 days at top speed in the game (unmodded about 115 m/s) to get from one end of the world to another.
Space is not open, while at present there are no planets, or even planetoids, (although planetoids are in the works), the world is littered with asteroids. Prior to December the world was only a few tens of thousands of kilometers across, and only up to 10 pre-generated random asteroids populated it. Now that the world is much larger, the program generates asteroids on the fly. They do this by only generating the asteroids that you can see, leaving the rest as just markers in the game file. When you get close to it, the game uses the seed in the marker to generate the same asteroid every time, when you leave it, the asteroid is de-spawned, to save on file and memory space. If for any reason the asteroid is changed, the asteroid remains loaded in the game file permanently. These asteroids contain a variety of ores. Some of the smaller ones may only contain one, while the larger ones could conceivably contain every ore in the game. Currently in the game is Iron, Nickel, Silicon, Uranium, Silver, Gold, Platinum, Magnesium, and Ice.
Then there's your character. A small (by game standards) 2 meter tall Space engineer whose sole task is to build things, and perhaps if PvP is your thing, fight other engineers' creations.
Those creations are, whatever you decide to build. You can build a large grid ship, or a small grid ship. Both ships are built block by block, like Minecraft, the differences are few, but noticeable. Certain types of blocks are only available for one size grid or the other. For example the Medium Cargo Container is only available for Small grids, while the Interior wall block is only available for Large grids. In a small grid ship, each block is .5 meters cubed. While in the large grid, each block is 2.5 meters cubed. It goes without saying that trying to build a 1 to 1 model of the Enterprise with small grid block would probably make anything but a super computer cry. A variation of the Large Grid ships, is Stations. Stations are only available in large grids, they are essentially Large grid Ships without the ability to move. (To be honest, I've never even tried to put a thruster on any station I've built to see if it actually would move, but the mass of the station would require quite a few thrusters to even try)
Physics: Newtonian physics dominate here. You tap a small ship, and it will move in the direction you tap it in. To counter that, ships with thrusters have a setting on the thrusters called Inertial Dampeners. If you have one thruster pointing in all six directions, the thrusters will make every attempt, while the dampeners are on, to bring the ship to a complete stop. (Remember that if you are trying to tow a ship, because the ship will fight against you) There are exceptions to these physics rules, for computation sake. If you build a long ship, say a 1x10x1 ship and put thrusters pointing the opposite direction on the opposite end of the ship. The ship will not spin, as one would expect it to. The extra physics math involved in trying to make that work like that was deemed too complex to actually work in a large scale environment. Not to mention being an engineering nightmare to people trying to build the ships. Additionally they added gravity generators in two varieties. The first generator is the standard generator the creates a (illogical) gravity pull on just one plane. The pull can be positive or negative, and it maxes out at 1g. Although you can stack standard gravity generators to create a stronger field. The spherical generator generates a gravitational field of up to 1 g, and it pulls (or pushes) away from the generator itself. Gravitational fields interact with each other to create some odd pulls at times. Only loose components, ore and players are affected by the gravity generators. Ships can be affected by gravity if they have an artificial mass block attached to them, but other wise they are not affected.
Vitals: The Space engineer has three separate vital signs that have to be monitored. Health, Energy and Oxygen. Health is obvious, the health of the engineer, hitting an object too hard, taking a bullet, or being hit by an active tool, and other things, will reduce your health, if it reaches zero, you die. Energy is the battery on your engineers suit. Until the addition of Oxygen 1 month ago, this was the big limiter on what you can do independently. This powered your suits life support, and any of the hand tools (welder, grinder, drill), and your suit lights and jet pack. If this reached zero, not only were you no longer able to use any tools, or use your jet pack, your life support system failed and you slowly suffocated. Oxygen: since the addition of Oxygen, energy has become a little less important, as this is now your life support, if your suits energy is at zero, and you have a full oxygen bar, you will not suffocate, although you may be floating in space waiting for someone to come and save you, and since you have no power, you have no comms, no beacon, essentially no way for you to be found. If you have a full energy but no oxygen, you will suffocate and die.
Oxygen in ships and stations: Ships and Stations can be built airtight, allowing you to pressurize them and walk around in the station or ship without a helmet. Your oxygen level will be set to zero, indicating that you have no helmet on, and you breath the station's air. Because you are not using suit oxygen, your suit's life support system isn't running and you use power on your suit a lot slower. A useful method of building delicate things is to build the outer walls first, pressurize the room, and then take the helmet off and work inside. Everything can be built by hand, or by a ship mounted welder, but some things are delicate, and an unintentional bump by the ship, will destroy it instantly. The downside of building things by hand is that it take a lot of time to build simply because you have an inventory limit, most things will take multiple trips from the cargo container to what you are building, while a ship mounted welder can pull items directly from the cargo container, making it so that you can build things faster because you don't have to go and restock as often.
PvP/PvE: There is limited AI in the game, as in very limited. The turrets on large ships are controlled by the AI, they can be set to shoot at certain items once they get into weapons range. By default they will target other weapons, other engineers and other blocks that are "owned" by an enemy faction. There are automated cargo ships that spawn in the world occasionally, travel a set distance, and then despawn. These are hostile to everyone, and occasionally they will fly near you and shoot up your stuff. That, at present is the limit to PvE, although they are working on improving the AI to include flight plans and active tracking. (at present these automated ships will do limited course corrections, but will frequently fly into asteroids if they can't pathfind around them.) Currently there are several weapon types in the game. Automatic Rifles are the only distance weapons available to the Engineer, although you can still use welders, grinders and drills to damage other engineers. Ship board weapons are interior turrets (which are short range weapons similar to the rifles) Gatling turrets that are longer range rifles. And missile pods, which fire unguided rockets. Small grid ships have access to Gatling guns, and rocket launchers. Which act like their larger ship counter parts, except that they do not track targets like the turrets do, and are incapable of automatic fire. Then there's creative weapons, guided torpedoes, mass projectors, etc. Stuff that in of itself is not a weapon (the torpedoes would have a warhead on them but the rest of the torpedo would be built out of armor and thrusters), but have been turned into weapons by creative engineers. I've seen someone create a wall of armor, put a few mass blocks on it, and then use a series of stacked gravity generators to fling the wall of armor across space, damaging or destroying everything in it's path.
I know they have plans in the next couple of months to have the game for a free weekend, I'll keep yall posted when this is going to happen. Otherwise the going rate for this game is $25 USD.