Thanks for the replies, always boosts my motivation .
Below I have tried to compile a summary of how I believe my game stands out. Keep in mind that we're discussing an early prototype, with a lot of malleable parts, as I am hoping that this thread will help me bring the ideas into a tangible shape. Being alone on the project, I lack anyone to juggle thoughts with, but thanks to the awesome gamedev.net community all hope is not lost!
My intention is to focus on what happens between the planets, rather than on them. No Man's Sky is a fresh and vast game which has inspired me from the start, but from what I can gather a large part of it takes part on the surface of planets. I would really like to explore the dangers and anomalies of deep uncharted space, the precautions you need to take to avoid being sucked into a black hole, colliding with a planet or moon, being engulfed by exploding suns, exotic hungry lifeforms mistaking your ship for a meal, or contradictions in logic frying your ship's computer.
In EvE online, there are hidden pockets of space with old relics and databankthings which you can access with special equipment. I would really like to expand on this concept. Not to mention the pirates looking for easy prey, keeping you on your toes.
I feel stupid for doing little to clarify my viewpoint on combat and player challenge. I often feel that games trivialize combat, making it part of a repetitive routine. I prefer an experience where combat is exilirating and terrifying, getting my adrenaline pumping and requiring my complete focus. In Chivalry, your weapon has great consequence. With a single swing, you can decapitate an enemy (or enemies), or mortally wound your teammates. I absolutely love this and cannot put the game down .
Judging from official footage, ELITE has an approach of including the environment in combat, inviting you to lure your foe into difficult to navigate asteroid fields and such. It is this kind of environmental hazard I would like to take further, defending yourself from the laws of physics rather than bloodthirsty sentient beings. I am attracted to Thaumaturge's thought that the universe is harmful to life, but players can help raise it.
Additionally, The Binding of Isaac and FTL are good single-player examples that force you into thinking before engaging, the risk being that you lose all assets and time invested in the game. The way I would like to handle player (im)permanence is to limit the assets the player can acquire, such as gear/experience points, but have death be permanent, a pattern seen in the games I just mentioned. The goal is to make the world interesting enough for interacting with/manipulating it to be a reward in itself, rather than provide arbitrary in-game rewards. I am thinking that if the player dies in an interesting place and he can keep the coordinates of his death, he can attempt to enter that region again (or go off in a different direction and explore something else). Maybe I am naïve in my approach, but this kind of reward is what keeps me playing Dear Esther, Proteus and Bientôt l'été. Some game worlds I enjoy exploring, but layers of arbitrary game mechanics break immersion and stand in the way.
I am not leaving combat out of the equation in my game, I see it as a terrifying rarity. When attacked in an unknown space, you cannot know what is going to happen. This happens in Amnesia and Dead Space. Using weapons for defense is a valid option, potentially eliminating the threat completely, but you are risking your life by not running. If the player has the potential to be malicious with his weapons, such as performing genocide, I would like that to have a consequence intrinsic to how the game works.
Naturally, the project is ambitious and out-of-scope at this point. I want to leave alternatives open for discussion with strangers on the internet, to inspire and be inspired. When I find out what appeals the most to me, I will pick a direction and base the game on that. For now, I am playing around with prototypes and really enjoying this friendly community .