Hello!

So far I have played this game for 17 hours.
I have spent 15.5 hours on hacking.

INFO
Because RNG, check all floors at the start of the game for assets.
Start a new game if something is missing.
(After a few tries, you'll know what to look for. (like water, fuel))

You can run down, past zombies to get stuff from the ground
and run back up to safety, but likely zombies will follow you.
No matter, saving the game de-aggroes them, so if a lot is coming after you,
save and quit, then hit continue in the main menu.

After day 8, the horde can not be stopped.
I had all 4 characters with chainsaws (50 dmg),
it was a slaughter, but even so, there were too many zombies...

TIPS
Sometimes restarting the game helps to get rid of problems.
A character can assist another making things a lot faster.
Grow food.
Use pause feature if you are looking at the building / stuff on the ground,
so you don't waste your in-game time.

GUIDES
Two guides from steam:
Let's Deep Dive: Food & Farming
Explanations of what and how in the game for beginners
(The latter google translated from Russian.)

BUGS
I think there is a limit on food plants. Above 6, the 7th plant does not give fruit.

You can carry 2 water bottles, but can only use one - have to place one on ground.
(The game does not fill all your bottles in the inventory at once,
also watering uses one bottle, when it is empty, you have to place the empty one on the ground
to use the next bottle.)

In one play I couldn't equip chainsaw unless the 2 guys were assisting each other.
In another all characters could equip the chainsaw without assist.

SKILLS

You can give max. 10 skills to a character.
You get 1 SP in the morning each day, around 04:00.
You have to spend SPs among the characters equally,
so you can't have a character with 2 SPs,
unless the others have at least 1 SP each.
(e.g. 2-1-1-1, but 2-0-0-0 is not possible)
Because you may only live 5-8 days,
you will only have 5-8 SPs.
That is not much, but there is a hack!

Each character has 21 skills, so to max all skills,
you would need 84 SPs.
You can only have 40 SPs.

Some skills are either useless or I don't know how to use them.
It is possible, that they are not implemented or just bugged
or need some item or other precondition to show up / work.

CRASHES and SAVES

There are error logs in
drive_c/users/<your_user_name>/AppData/Roaming/Solar Powered Games/Highrisers/log/errors
They give a stacktrace which explains why the game crashed.
e.g. DO NOT save & quit while
- watering plants or getting water from a barrel.
- a building display is open. See pic.
It is best if noone is doing anything, just standing around.

If the game crashes after starting the game and hitting continue in the main menu:
Check the error log.
Sometimes the 2nd or 3rd try loads the game properly.
In some cases, like
if you have saved while watering, the saved game may be irrecoverable!

If you play a game, make a mistake, save & quit, Alt+Tab,
replace the savegame file, Alt+Tab,
hit continue in the main menu,
your last game will be loaded from memory,
NOT the replaced savegame file.
You have to quit the game fully and restart it to load the savegame file.

You SHOULD MAKE REGULAR SAVES and BACKUPS of the
drive_c/users/<your_user_name>/AppData/Roaming/Solar Powered Games/Highrisers/autosave.sol
file. Like every 5-10 minutes.
(save & quit and backup autosave.sol)
(On linux:
7z a "hr_save $(date +"%Y-%m-%d %H-%M-%S").zip" autosave.sol
command in the savegame folder creates a date + timestamped zip file.
Similar can be written for windows.)

HACKS

In the game folder, in the data directory, there is an assets.pkg file.
This is actually a zip file.
You can rename and unpack it.
Inside, loca/locaTexts.csv holds localization data.
This has reference string in the first column, that you can search for,
while disassembling Highrisers.exe.
Inside, furnitureGroups folder files hold various in game objects.
It is written here, what recycling something drops!
e.g. Changing the chargeLevel for BarrelWater in fg_waterbarrel.fg and fg_industrial_y_03.fg
to 2500 can drop a water barrel with 2500 capacity in the game.
(Not all water barrels will be 2500 though...)
(Same can be done for fuel barrels.)
(You can actually give yourself whatever you want changing things inside these files!!!)
After the changes repack / re-zip the file and rename to assets.pkg

Because 1 skill point per day is pretty limiting,
I have found out, where I can change that in the main game executable, Highrisers.exe.
See pics. Both have been already changed.
The original code is:
C7 05 AB 7F 5B 02 01 00 00 00
NOTE that you should not set this to a value above 40 (0x28 in hex),
because the game does NOT let you exit the skills menu
if you have unspent skill points!
I haven't tested what happens after you have maxed out skills on all characters,
so save before dawn. (and put back original .exe or set skill points per day to 0)

I don't know how to change the max. skill level is 10 setting.
Probably there is a skill array for the characters that is only 10 spaces big...

HACKS

You can change keys if you find where they are set up.
I have only looked at switching P key for pause / unpause
with SPACE key for picking up stuff.

pause button set from P to SPACE
or:
1400b3c29 ba 50 00 00 00 MOV EDX,0x50
new:
1400b3c29 ba 20 00 00 00 MOV EDX,0x20

unpause button set from P to SPACE
or:
141ca0b91 ba 50 00 00 00 MOV EDX,0x50
new:
141ca0b91 ba 20 00 00 00 MOV EDX,0x20

pick up button set from SPACE to P
or:
1400b3cfb ba 20 00 00 00 MOV EDX,0x20
new:
1400b3cfb ba 50 00 00 00 MOV EDX,0x50

The pictures show the changed values in ghidra. (Highrisers.exe)
(This is for the GOG version. setup_highrisers_1.0.5.f_(64bit)_(51492).exe)

TODO

Based on the Highrisers.exe, there is an in-game cheat menu.
I don't know how to activate it...

I wanted to get rid of the logos at the beginning of the game,
but so far I couldn't.
A logostate is created in FUN_1404236a0 with the images,
but I'm not sure how to skip them...

FUN_1411c1b80 has many game options like zombie respawn time,
but I'm not sure if these have an effect or how to use them...