First I want to say that there are so many things incredibly right with this game.
The terrain tool
Art and lighting
Procedural uniqueness to every new game world
loot handling, backpack, interface on the world.
Outstanding polish put into subtle things, like how a storage unit fits on a truck.
I am sure that some of my suggestions aren't in line with your plans, but keep reading. Wide variety of points.
My list of suggestions and bugs:
Habitat earlier in research.
Maybe after truck.
Shuttle should be researched
Maybe after habitat.
More important excuses to use the well made terrain shaping ability.
Currently the funnest use is to build a barrier against a storm. It feels necessary and useful.
Falling through the ground is obviously a really common issue and very easy to replicate by building terrain around yourself until it closes in.
When you die by falling through the ground, at least for now, move the body (backpack) to the planet surface above the location of death.
Console commands available to players during alpha.
There have already been many cases of hours of work lost for one reason or another when a fatal issue made someones save unplayable.
Subnautica is a good model for the kinds of console commands to include.
Building space stations with some helpful purpose.
Research, communications, power beaming from one place to another, etc.
Most importantly, and most difficult, we really need something that motivates us to generate our own content.
I've spent some time thinking about it, but I haven't worked it out yet, and I don't know the limitations of the engine and game design.
More reason to go to other planets.
Research, resources, etc only available there.
Research for upgradable suit and backpack
Make suit upgrades required to handle different planets
Maybe even just modules that have to be equipped to filter or block harmful things.
Upgrades to the terrain tool.
Extra functionality, faster, wider, etc.
Resource node markers remaining after all resources obtained.
Despite digging and absurdly large hole around the node, there are no more resources.
Destruction of modules and vehicles, obviously.
Compound the "horsepower" of connected vehicles so that trains works better, because they are fun.
Some in game list of things you have researched.
Run faster with mattergun holstered.
Some generated worlds have a lot of seams in terrain (places where the geometry doesn't align along the polygon seams.
Disable clicking a backpack when it is on your back.
We have Q for that, and it can be annoying.
Consume more oxygen when running.
Construction on suit should consume energy.
Is the delayed motion of objects carried by the cursor as fast as it can be while still not break the physics too bad?
Different button for pointing to something vs shift picking it up to your backpack.
Late game researchable method of field research.
Some way to research things in mines without bringing them out one by one.
Teleporter, backpack feature.
Adding an ore block to the smelter while it is smelting causes and incomplete block to form on the output head.
Once this incomplete block is forces off of the smelting head by a different ore type, it becomes an uninteractable partial block on the smelters side inventories.
Storms should activate wind turbines.
1-Seat made by vehicle assembler should be removable.
This game has the same issue RimWorld had, where you would spend hours on a wonderful save, only to have its complexity eventually make it unplayable.
It is fundamental to a game like Astroneer to have the ability to work on a single save and build a giant complex empire without end, like minecraft.
Memory leaks or something like them.
Whatever it is that makes restarting the game a good solution to performance drops.
Make objects stop running physics simulation after a threshold of low velocity.
For example, a cluster of energy when set on the ground continues to run physics when it is essentially sitting still.
A solution is to shut this off at low velocity until the object has a certain minimum force applied to it.
S̶o̶m̶e̶ ̶c̶o̶n̶t̶r̶o̶l̶ ̶o̶v̶e̶r̶,̶ ̶o̶r̶ ̶m̶o̶r̶e̶ ̶c̶o̶n̶s̶i̶s̶t̶e̶n̶t̶ ̶d̶e̶s̶i̶g̶n̶ ̶f̶o̶r̶ ̶w̶h̶e̶r̶e̶ ̶b̶a̶s̶e̶ ̶n̶o̶d̶e̶s̶ ̶e̶x̶t̶e̶n̶d̶ ̶t̶o̶.̶
T̶h̶e̶y̶ ̶s̶e̶e̶m̶ ̶t̶o̶ ̶g̶o̶ ̶u̶p̶ ̶o̶r̶ ̶d̶o̶w̶n̶ ̶i̶n̶ ̶e̶l̶e̶v̶a̶t̶i̶o̶n̶ ̶n̶o̶t̶ ̶f̶o̶l̶l̶o̶w̶i̶n̶g̶ ̶t̶h̶e̶ ̶t̶e̶r̶r̶a̶i̶n̶ ̶o̶r̶ ̶s̶t̶a̶y̶i̶n̶g̶ ̶l̶e̶v̶e̶l̶ ̶w̶i̶t̶h̶ ̶t̶h̶e̶ ̶n̶o̶d̶e̶ ̶t̶h̶e̶y̶ ̶c̶a̶m̶e̶ ̶f̶r̶o̶m̶.̶
S̶o̶m̶e̶ ̶r̶e̶s̶e̶a̶r̶c̶h̶ ̶o̶b̶j̶e̶c̶t̶s̶ ̶d̶o̶ ̶n̶o̶t̶ ̶p̶l̶a̶y̶ ̶n̶i̶c̶e̶ ̶w̶i̶t̶h̶ ̶t̶h̶e̶ ̶l̶a̶r̶g̶e̶ ̶s̶t̶o̶r̶a̶g̶e̶ ̶u̶n̶i̶t̶s̶ ̶(̶t̶r̶u̶c̶k̶s̶ ̶a̶n̶d̶ ̶s̶h̶i̶p̶s̶)̶.̶ ̶
P̶h̶y̶s̶i̶c̶s̶ ̶g̶e̶t̶s̶ ̶u̶p̶s̶e̶t̶ ̶h̶t̶t̶p̶s̶:̶/̶/̶y̶o̶u̶t̶u̶.̶b̶e̶/̶i̶_̶C̶I̶1̶m̶e̶9̶9̶9̶4̶.̶
T̶r̶a̶d̶e̶ ̶i̶s̶ ̶O̶P̶