What I'd hope for in regards to the question I've asked for Q&A mentioned by the OP would be something like like modular design in a way of combining preset elements of all kinds of equipment. Since I feel like letting my imagination go, I will write down one of the few systems I was wondering about, along the lines (meaning, stuff probably would use input of others) of what I'll write down there. Bear with me, it won't be that much of a short post, but I'll try to explain an idea thoroughly. This won't be only about weapons but about modular system of equipment in general.
I'd first divide the equipment into several categories. Let's say simple setup of helmet, armor, handgun and rifle would cover most of what people would need, allow degree of customization without bogging the whole thing down with a lot to try to keep it simple but potent. Intentionally I wouldn't want to use such system for stuff like handheld mining equipment as I believe that system of 'get tier 1 drill to mine this, make tier 2 to mine that' would be neither fun nor really useful in a world where people strip-mine planets.
Then, have each item come with few elements, for example:
Helmet: Visor, Shell, Additional
Armor: Shell, Jetpack, Additional
Handgun: Frame, Muzzle, Magazine, Sights
Rifle: Receiver, Stock, Muzzle, Magazine, Sights
That should provide decent customization while making it simple.
Each in each element's slot now, one of several designs could be used for a module, offering different stats.
For helmet:
- Visors - depending on the design used, visor could offer additional protection against damage at the cost of visibility (vision glitches? dim or color-tinted view?) as well as offer different UIs (mostly meaning listing of targets with info regarding distance, speed of the object etc). Thus, one could get some sort of reinforced combat visor that is somewhat dim but gives the user decent protection, with rather minimalistic UI and slightly limited vision (view going through some filter, bars across the screen etc) or some scout visor with great visibility, ability to get a zoom in, UI with some additional tidbits of information about targeted object. Then, few models of everything in between, from cheap but decently sturdy visor that wouldn't have a decent defogger making fog temporarily condense on the surface from time to time to something between all aforementioned.
- Shell is the whole 'package' - dictating the resistance and weight of the helmet. Different designs of shell dictate the base defensive rating of the item, affect it's decay under severe condition (resistance to acid rain, radiation etc) and bulkyness (limited speed of turning?).
- Additional would be little non-vital gimmicks that'd improve certain features of the helmet or give it new functions. Poison filters, advanced rebreathers making oxygen supply last longer, mounted lights of different strength, frame reinforcements for those who want even more defensive potential or an encouragement to headbutt incoming missiles.
Armor:
- Shell could have exactly the same properties shell of a helmet does, just with overall bigger effect on character's 'stats'.
- Jetpack is basic propulsion system, necessary for spacewalk. Different modules could allow different speed, use of energy, responsiveness/class of stabilisers (one module could stop the player nearly instantly after letting the key go, other would decelerate very slowly) or even change a bit of dynamic of flight (continuous, smooth flight which could use up the energy rather quickly vs jetpack creating periodically bursts of push in the direction the user specifies).
- Additional. Similar, with differences, to helmet's additional modules slot. Ability to mount lights, additional protection layers against certain types of damage, servomotors increasing speed of of running character.
Handgun:
- Frame - The base of the pistol. Governing to a degree the rate of fire (time between shots as well as 'mode' - whether it'd make single shots or, say, bursts of two shots per pressed mouse button?) and damage.
- Muzzle - Stabilizing the gun, main effect on accuracy, at a trade-off of rate of fire or damage dealt.
- Magazine - Energy consumption of the gun per shot, energy recharge rate, maybe a choice to actually have a gun (at least audio-visually) shooting bullets (invisible projectiles with less-sci fi sound effect) rather than beams of energy if someone wants such.
- Sights - Again, effect on accuracy, worse or better aiming crosshair, maybe actual ability to target with sights a'la typical shooter.
Rifle:
- Receiver - What frame is for the pistol. The main element which makes one rifle be closer to a shotgun while other is more of an assault carbine.
- Stock - Weight, bigger effect on accuracy than it is in case of a muzzle/sights (if only to simulate through overall bonus that rifles are generally longer range weapons in comparison with pistols), looks.
- Muzzle - As in handguns.
- Magazine - Likewise.
- Sights - And again, I'd imagine the function would be very much like in case of a pistol.
