Here I shall describe my Mother Spaceship concept. My goal here is to achieve physical realness, except for the energy generator, hyper-drive and other technical details about interplanetary drives, etc.
1) The ship is several kilometres in length and between 100-200 meters in diameter.
2) The ship uses a rocket engine propulsion system. The engines are identical and placed symmetrically on the ship. In addition for reasons of realness the ship is similar in layout to a skyscraper building, instead of the submarine design which we are so accustomed to seeing in games and movies. The engines are at the bottom of the ship and therefore when flying with acceleration, the "gravity" will be directed "downwards" towards the engines.
3) Engines and tanks contain a working substance in them (the reactive mass), which occupies 30-70% of the ship's volume. It is important to consider how the engines are arranged, as they're not chemical, I.e. the energy source and reactive mass (working-substance, propellant) are different things. The engines are very powerful, and can accelerate the ship to 5-10 G, and has a stock characteristic speed ("delta-V") in the order of 1000-10,000 km/s from just one refuelling. (It gives the ship ability to change speeds. I.e. the ship can be accelerated to 100 km/s and stopped several times just from one refuelling). The working substance is crystallized hydrogen, water and some other thing that can be easily collected from space.
4) The energy plant is a separate reactor or combined with engines (fusion engines allows to produce electricity). In the second case, some energy batteries (quantum condensers?) are needed to power ship systems then engines are shut down.
5) The external part of the hull is covered by heat radiators for engines, reactor and habitation/cargo modules. Radiators for engines, reactor and habitation module are different, because they work with different temperatures.
6) There is an anti-meteorite shield in the forward part of the ship. Flying at a speed of 1000 km/s in the interplanetary zone will create the effect of a continuous bombardment of sub relativistic micrometeorites. The shield itself may need to be replaceable, or have separate replaceable modules, or maybe have some kind of magnetic energy shield. The shield should cover all parts of the ship against the flow of space matter; it is therefore necessary to place it more compactly and closely to the longitudinal axis.
7) The cargo and habitation modules are placed behind a meteoric shield, surrounded by a radiation shield. On its surface there are different hatches, air-locks, hangars, viewing decks, telescopes and other sensors, weapon loop-holes etc. What's important is that it's all covered by the forward meteoric shield.
8) If rendering for indoor-scenes are implemented in the engine later, it will be possible to model the interior layout of habitation module. Then it will be possible to walk around the ship too. The ship's layout is similar to a skyscraper, with an internal system of transport (with lifts and escalators). The direction of the floor would run parallel to the length of the ship. There are hand-rails and short flights of stairs located on the walls to aid movement in weightlessness when engines are dis-engaged. At the center of the bridge is the control center where everything is managed, with its panoramic displays, armchairs, diamagnetic jacks of inertia and other such things. Monitor displays would be holographic and look like windows - the player will view external space through such monitors. It would be interesting to conceptualize another layout mode with artificial gravity with the rotation of the ship around the longitudinal axis, where the external walls will become the floor. It's possible to make some parts of the habitation module rotatable: When the ship accelerates, gravity will be directed to the floor of the module, but when the ship shuts off its engines it will switch the habitation module into rotation mode, the module will turn at 90 degrees, so centrifugal "gravity" will again be directed to the module's floor. Windows aren't present on the ship, only the special observation deck will have them. And of course, windows will not be on the external part of the meteoric shield
9) The ship has on-board factories, where new shuttles, modules and other devices can be manufactured using resources taken from planets or synthesized by on-board nuclear-conversion reactors.
10) The ship can fly faster-than-light. The currently approved concept is the Alcubierre warp drive, so ship must be equipped with two or more large "hyper rings". Look for the default SE ships called "Explorer-1", "Explorer-2", "Doctor Ship" for reference.
11) The Mother Space Ship cannot land on planets. Instead it carries various shuttles, specially designed to fly from space down to planets with atmospheres or airless worlds. Besides shuttles, there are also some repair, cargo and harvesting vessels.
12) There are special vessels with a ram-scoop for collecting hydrogen from atmospheres of gas giants (hydrogen is the propellant for the main engines). Though it is possible to place a ram-scoop behind a meteoric shield. The shield opens up as a bud and puts forward a ram-scoop. Another way to resupply the main ship is by using collector boats for harvesting, for grabbing ice formed comets or icy moons, etc.
13) There are no limitations on the number of polygons for the models, due to development of technology of adaptive and/or procedural detailization of the ship and its parts. In the beginning, it will be possible to make each part of the ship's model with an independent set of LOD's. The ship would be built with several replaceable modules - engine, reactor, cargo etc. So this shall provide a good system of upgrade for the ship later.
Ships with Alcubierre warp drive:
A few old sketches:
SHW - 2
SHW - 3
SHW - module ship