Just to start this is a list of random things that i personally think would add to SK, some possible, others less so but still

im going to start with some of the simple things that would really make my day to see in SK, and yes the majority is new content which we all so desperately want all the time anyway

-Piercing gun-
it boggles me that there is still no non-event based 5* piercing gun that does not lock you in place while firing (to my knowledge or on the wiki if they snuck one in i would really like to know about it) considering the monsters weak to piercing (beasts and fiends, those dirty rotten devilites) constantly moving is the single most important thing, between lag, their constant dodging and relatively fast attacks being locked in place while firing more often than not means taking a hit when facing even a medium sized mob
as such a non-heavy piercing gun would be super appreciated, a third antigua line seems most likely/realistic but if thats not going to happen a piercing gun based on the style of the blaster would be just as nifty, though a different charge attack would make more sense, a piercing beam that damages all monsters in a direct line (terminating early if it hits a block or obstacle) wouldn't go astray but a decent alternative would be to have the charge fire 3 bullets in spread like a T2 gun puppy
appearance wise i see no problem with reusing a re-coloured antigua or blaster, but a scope would more fitting than a bayonet for the 5* version
alternatively why not go with beams, just longer versions of the seraphinx's ray of light, but single bursts, since it has potential to be a bit OP (damaging every enemy in a straight line) damage would have to be lower than other guns

-battle sprites-
Valestone and moonstone are currently pointless, perhaps this is getting fixed with the arcade redux but as we have no idea...
lets get some more battle sprites happening
Yes developing sprites is a lot of work since they have to be useful and look adorable/cool/spooky/interesting and need 3 reasonably unique skills
I actually only have one idea but its a start eh.
we know that they are robots underneath their fairly organic exterior so lets have a mini robot to aid us on our never ending quest of cradle. It will probably be for moonstone since constructs do actually drop blue shards
as for appearance i actually quite like the sprite that hangs out with the lead biotech NPC, its kinda generic sure but it looks like what i can imagine apple products becoming if they ever took the form of small floating robotic ai companions
Skills
since we have already covered basic attack, support and debuff lets go with area attack
as its a construct it should focus on shock
skill 1) discharge - place a bomb attack either on the knight or just ahead with a very short fuse and mid AOE, the graphic need be no different from the standard blast bomb - variant to add shock status or cluster bombs
skill 2) static barrier - same as the drakon's flame barrier but shock - variants know idea
skill 3) never really got that far only had the first 2 skills worked out but something that deals low damage to a large area or applies shock. or both

-Prestige-
HUGE let down
in its current state prestige is fairly pointless to my knowledge
A) achieving the prestige ranks should carry over to achievements - they basically replace the deposit ore legacy achievements as massive grind fest/time spent awards
B) add prestige to arcade runs - i would suggest adding prestige to every depth, completing any T1 depth awards 1 prestige, any T2 2 prestige and any T3 depth 3 prestige, possibly double for boss missions, which just allows knights to accumulate it marginally faster but also promotes it, the more you see it increasing the more you will be tempted to actively progress it thus playing more SK, since you're still looking at less than 30 prestige for a full T3 dive the daily prestige missions are well and truly still worth it, especially as they will provide bonus prestige for each depth on top of the completion bonus
C) make it useful, nothing that truly changes gameplay or anything but as goals to work towards for this i have 2 ideas
1] add a perk to the knights, exactly the same as the sprite perks that unlock at certain prestige milestones, every thousand or so seems acceptable currently though incrementing values might provide more longevity
-or-
2] reaching prestige levels, either the existing ranks that add the little icon to your name or new, more plentiful ones, award a prestige award prize box that contains 1 random item selected from; materials, tokens, rarities, standard accessories, special prestige costume pieces or unique prestige equipment (read specially reskinned cobalt set) all between 3* and 5*. of course anything else could be added to the list but having the materials in there means that the majority are not giving away anything of any real value, but its prize boxes and people looove prizes

-weapon variants-
this is the most whimsical item on the list, a bunch of new weapons that are little more than reskinned existing weapons, new charge attacks or animations would be great and all but...
honestly i just want to see some axes/hammers/scythes/spears to replace the swords that everybody carries so that there is more variation in the appearance of the knights (yes i am that petty) virtually everyone has an acheron or nightblade so it would please me no end to be doing a dive, get to a slime level, everybody switches to their acheron or grand faust and just one person pulls out the shadow axe, which acts exactly as a nightblade in every aspect it just looks different
small spears could easily replace flourish line weapons and hammers could replace the massive troika line swords, and look just as badass

-personal place-
possibly the largest addition, player housing
and its not undoable either since the base functionality is already implemented with the guild halls, i just worry there may be some limit to the amount of data being stored per knight, if suddenly everybody has their own personal knightly pad thats going to skyrocket
Honestly though it could be quite a boost for SK and the community since player housing always draws more people in and they are willing to splash out for vanity projects (we see this quite clearly with the amount of costumes around). Since we are already playing virtual dress ups why not add in a bit of virtual interior decorating

something along the lines of
*The scouting parties sent out by spiral HQ have uncovered various segments of the clockworks that never seem to move too far from haven. After carefully mapping out their course Spiral command has given the all clear to settle there. Any knights wishing to own their own piece of cradle should report to the settlement engineer in charge *new NPC* Good luck*

add in 2 or 3 missions to 'clear out' these new bits of cradle that are luckily near the surface and never move far from haven then every knight can have little pod to call their own.

honestly i was thinking of incorporating the ready room into player housing, each time you start up SK you appear in your own home (once acquired) beep booping at the consoles but you can then run around once you close the news/mail window
the home would consist of an entry way, obviously, probably leading straight onto haven central plaza, the ready room terminal on one side and a room for you to decorate as you see fit, probably 5x5 or 8x8 or 10x10 tiles

then to keep things interesting having the option to not only furnish the room but change the decor as well, pay large sums of crowns to change the floor and wall textures, possibly even the ambient music
and then furnishings, purchasable from vendors of course for some but adding furiture recipes would be a good way to use up even more materials, and if necessary require orbs of alchemy to make people pay real money for it, obviously crowns and materials are preferable over using orbs of alchemy but whatever gets it to happen

-challenges-
seems to be the current theme on the suggestion forums so sure why not, an extra daily (weekly?) mission that offers prestige and considerable pay out, a large treasure room at the end would make it worth while
personally i was thinking of challenges like the danger arenas though with a few alterations;
-none of the monsters drop loot, only buffs , vials and vitapods and hearts - all the loot is stored at the end in treasure chests
-no revives, at all, you die you return to ready room/haven with nothing and have to wait till tomorrow to try again (in a group everybody is kicked once the last person dies otherwise everybody revives, may need to make the treasure on a separate floor, no joining allowed once the party has descended to the challenge floor from the terminal)
-could make gauntlet runs that involve no killing but instead drop all knights health to one pip and require them to safely navigate a gauntlet of floor hazards, traps of various kinds, missiles mortars, lasers, giant flaming wheels of doom, and invulnerable ranged enemies, rows of gun puppies! and the occasional fairly simple puzzle (these spikes are moving this way now so if i hit this switch...)
-timed missions, probably candle light keep missions though any would really be fine, timer starts with party button at very start of mission, monsters drop no loot, party is kicked if all die(no revives, or maybe just no free revives) or if they fail to reach the finishing party button before time runs out, large treasure room on the floor below, no invites, no joining after the mission terminal

-Radiant silverhelm-
this one is very simple, it is still missing, the lovely golden helm to go with the lovely undead butchering golden mail is still not around, i think it should be

-Level mechanics-
like candlelight keep if some levels could have unique mechanics it would really liven things up, there are a few around already of course, the swarm levels, candlelight, graveyards even but im sure there are a few ideas over the years that could be implemented and would brake up the monotony of the clockworks levels
for this i have a few ideas
-limited air, either underwater or in a random vacuum that happens to exist within the clockworks or an area so heavily saturated with evil that it sends knights insane each knight has a limited, air, pressure, sanity, bar that depletes while not in a 'safe' zone, once empty the knights health slowly drains until the bar can refilled at the next 'safe' spot (once use air bubbles or whatever would be a nice touch), adds a touch of urgency to the level and its harder to avoid than the grimalkins
-stealth missions, a few of the mission descriptions involved sneaking in to places but all we really did was run headlong at the front gate blasting away so why not incorporate missions that involve a level of sneakyness, each time a knight is caught in the spotlight of specific search beams a gate to a few treasure boxes at the end of the level shuts and a few lootless mobs spawn. in between the search beamed rooms there would still be regular enemies to fight and basic clockworks rooms its just to get a small treasure bonus you have to avoid spotlights and/or not attack specific 'sentry' monsters
-crumbling ruin/raging fire/toxic flood, similar to limited air this is about urgency, the level progresses in a single direction, random offshoots never being too long as some form of inescapable destruction follows along slowly engulfing the level, the knights have to run ever forward or risk their life. Fire makes the most sense as the level isnt truly destroyed but any knight caught in it will die eventually whereas a crumbling level would be far more difficult as the level itself is destroyed and if a knight does fall behind the line do they die instantly or ...
-courier, whether be required to complete the depth or simply open a special treasure room the knights must bring a object, like a statue from the begining all the way to the end, but its fragile, enemies can destroy it, they would treat it the same as any knight attacking it if its the closest target. would require a bit of balancing as the target cant be too tough or its to easy but too fragile and solo or groups of 2 might not be able to complete it realistically
-protect, similar to courier in a way as you are tasked with protecting a convoy/research team/spiral orderly through the level, with 1 or 2(or 3) pit stops to allow an arena with a few waves. to make it more interesting some enemies will only appear when the protected unit comes close whereas most will spawn as soon as a knight comes within range same as normal (so its not broken the protected unit would have to be immune to floor hazards or run off down a separate path that the knights cannot take instead forcing them through the hazardous traps and 'devious' puzzles, just like the rest of the clockworks)

that's it for now, my cat still demands attention (and food)
criticize and abuse to your dark little forum posting hearts content
(but seriously, im absolutely sure there are problems with some of these ideas so some helpful suggestions/constructive criticism would be appreciated)
(infact some feed back any form would be appreciated)