A list of suggestions

[ANOMALY337]

before we start, in my opinion an interface, UI or GUI should always be consistent where possible, so that each time you press a button you can expect and predict the same result

neutronium heat should always default to subzero, as it has infinite heat capacity, but mainly because it makes spotting geysers easier with the temp overlay

middle mouse click rotates buildings, like "O" key (support mouse3 binding)

cloud save games

express selves expression database entry, describing every emotion/expression

dig, clean, other duty assigns, numbers work like priority duty assign (changes duty priority, not building type)

in the duty assigns, "harvest" and "disinfect", each time the button is pressed, cycle through different options, e.g. enable harvest, disable harvest

selecting building, (breaks GUI consistency)
    first number entered selects building type
    second number entered selects specific building
    third number loops back to being first number (select building type)

pressure overlay

elements overlay, in addition to gases and liquids, add fluids (shows gases and liquids)
elements overlay, can select multiple filters

when starving and at zero kcals, deplete health at a rate of something like -200%/cycle (balance as needed)

there's a mod on the steam workshop called "pliers" that disconnects two neighbouring tiles of pipes/vents. put in game (like pipe extract duty)

"[" and "]" tabs between tabs in the selected item panel

make tutorial or make clear that either flying critter traps can be used and CRITTER DROP-OFF CAN WRANGLE FLYING CRITTERS. if critter drop-off auto-wrangle allowing wrangling flying critters is a bug, please don't remove and support it instead (plastic traps that break or are one time uses is harder, but your choice whether to remove critter drop-off flying critter wrangling)

can build tiles over ladders. maybe allow building doors and ladders over tiles? (please reply to me if you don't want to support this)

[need to test myself, see the actual exchange] can we fix the electrolyser(from uk, is it z only in us?) destroying heat, by retaining temperature but when water of heat capacity converted to hydrogen and oxygen, the sum of heat capacities of H and O are less than H2O, but the temperature of H and O are the same as H2O so heat energy destroyed? (is the excess heat dissipated to electrolyser building?)

optimise cpu load, if not done already, getting high load on cpu on a mid-range laptop (although I got a desktop that has no trouble with the game)

deconstruct filter should default to "buildings", in my opinion

cancel filter, add "buildings + sweep + mop + dig" filter, so can cancel builds, digs, sweeps and mops without affecting the piping and wiring, etc

when selected building, numbers change its priority, rather than select building

when selecting fabrication orders, clicking on an item should auto-focus the quantity entry box. clicking on quantity entry box should always highlight all characters (consistency). entering numbers should immediately be submitted, resubmitting and additional numbers entered, and not require that you hit enter for the number to be submitted

consumables panel should have "fullness", "eaten today" and "health" (helps if implementing the "0 kcal reduces health before death" suggestion) fields from the vitals tab. moral isn't as useful, I guess it is for food moral bonuses
this will help when users have a starving colony, and need to micromanage who gets food first

priorities panel, boxes should be numbers instead of arrows and box fill increase in colour from white to green, yellow, amber, orange and red (traffic light) so it's visually more clear. also conveniently lines up with the actual decimal numbers of priorities for errands
duplicant skill level can be indicated by box border colour, from a black or grey, to a yellow. (I got this idea from rimworld, see game for reference)
default priority start at 0, rather than in the middle (3?)

in schedule panel, making new schedule should copy the schedule above it
in schedule panel, clicking a duplicant should display a small version of just the schedule boxes, making it easier to identify each schedule (include morning and night icons)

loud sleeper trait should be displayed on beds and in the schedule panel, to make it user friendly to identify and manage (I guess could sort when spawning a duplicant, placing them in a particular bed, but I don't like going through every duplicant bio and watching when they sleep to see if they are waking someone up)

maybe exo-suit checkpoints should have an increased travel cost when calculating most available errands, because I see a lot of duplicants doing one or a few constructs and digs, then leaving. maybe construct material storage on the suit side may help with that? just thought I'd mention this increased travel cost

maybe bug, germ overlay for pipes and vents not showing each tile of pipe contents. also showing pipe/vent surface germs rather than content germs

make dup death sound more obvious/dramatic so user is more aware. 
(inspired by rimworld) have momentary icon notifications pop up, before contracting to their text notifications in the top right. things like "starving", "suffocating", "insufficient oxygen" and "scalding", etc. not routine notifications like schedule alarms though, would dilute and obscure/obfuscate the important notifications

can we have the number of germs, of each type, a dup is exposed to in the germ overlay and item panel - germ tab? or is that hidden to make the game harder?

an overlay where we can type notes and draw for blueprints/plans?

in dup movement tutorial, include the movement images, including doors, from image attached (source: https://oxygennotincluded.fandom.com/wiki/Duplicants)

automation weight plate can be built over tiles, like tiles over ladders

optimise many critter path-finding impact. I mean, they're just wondering about 90% of the time, what thought is needed? is the path-finding search range limited to something like 3 tiles?

I thought it would be better to compile these suggestions rather than make a tonne more, sorry if this was incorrect. 
I would like to hear views on this, and sorry if I mentioned one already being looked at, or already declined.
thanks for reading, hope this helps,
ANOMALY (Alex)

[Sasza22]

Nice suggestions. Most of this stuff was requested. Some even worked on. Bulding tiles over ladders and vice versa was in testing for a while but was disbled due to bugs. Hopefully they try to add it back at some point.

[ANOMALY337]

I just realised can use priority assign to spot geysers. oh well, the sub-zero temperature would be another nice way to spot them. also, thanks Sasza22

[Tobruk]

Thanks for this extensive list of suggestions. Let's hope at least some of them get implemented