The good thing is there is basically no missable achievement if you play normally, and though storywise you have two path in later chapter, they both lead to same ending, and same achievements unlocks.

But!! there are some event related achievements that can be locked out if you pass on a certain part of the story too fast. ie. the tournament rankings. i think this is more of a bug at current version, since some part of the event will run, but the main opponent just doesn't spawn, etc.
so i'd suggest to make some backup saves periodically. esp. before fighting for rank 1 in the tourneys, since that is the chapter divider.

The game itself does not have a game over, any opponent that you cannot beat will still be there, giving you chances to improve yourself before challenging them again.

There is a simple method of save scumming (at current ver 22jul'23, not sure if this will be patched later) so before a big fight, save the game manually. if you lose, go to map, menu, and pick exit (it will exit without saving). this will give you basically a second chance to re-challenge the fight without losing time ingame. sometimes, just changing your approach will net you the victory, but if you are severely under-spec compared to your opponent, maybe just accept the loss and improve yourself first..

If you are softlocked somehow (ie. no energy to work, no money to buy food) talk to your mom/casey/henry..

Note: If you played the demo, you may found some achievement not unlocking, unfortunately you need to start over with a new save. Good news is you will get a pet if you make a new character (if you get the preorder dlc)

• In the earlier days, i would suggest focusing on one stat, either str/agi/stm, so you can pick a school and get a better style. There is basically no wrong decision here, so pick whatever you like..
  
• For happiness, open your daily top kek jokes and pet your cyberpet, i find it enough until even late game. This in early game will save you money from buying sodas. Happiness will affect your efficiency, including those happy/sad faces when you are excercising.
  
• Try to get 2 promotion on the work places before getting rank 1 in Silver League, it will help you a lot in chapter 2 later. Don't forget to install the software for each place to get the max benefit
  
• Use the food buff from the work place that is suitable to your style if you have a tough time
  > noodle: mental balance (+5% dodge chance, -10% energy consumption)
  > slimeranch: melange (10%block chance, +25energy between rounds)
  > junkyard: battle trance (-10% undefended damage received, +15hp between rounds)
  
• Try to fight all opponents, especially if they looks unique, since they may trigger some events, ie. Ruth in silver league, skipping her may make you stuck in the questline

Such a strange dream…
So far, only one thing is clear - you need to find the father. -- finish prologue cutscene




Your first fight
Better not to remember how bad your arms shook. -- after the first fight at Apu's store




Good Person Chip
Can this device read my thoughts? -- after the cuscene where you get the chip implanted at Police station



First winning
You feel adrenaline in your veins. -- win for the first time




Your first job
Now you can see that getting a job isn't that hard, right? -- go to noodle man/ bobo/ russian junkyard go get a job



Depressed visitor
You met K. He seems mysterious a little -- meet K the ex cop at Club Street/Noodleshop



Neurotrainer – power gainer!
Who said the gym doesn’t require brain, huh!? -- train one time using neurotrainer in Silver's Gym




Old movies enjoyer
There’s something marvelous in those VHS films -- buy your first VHS at Apu ($100)



Intriguing candies
These candies help your mom to sleep -- get some candies from Apu to help Player's mom to sleep. (was bugged, but i think the hotfix update fixed this achievement)



Your own amateur gym
buy your first trainer from Grisha at Junkyard ($150)




Run K, run!
acquired after the cutscene when you bring K's badge from sergeant to K at Club Street



No bullying more
You taught some manners to that guy. -- Defeat Huey (rank 9) at Silver's League




Pal of your father?
You met Casey, he could help you find your dad. -- acquired after beating Skinny Jenkins (rank 7) at Silver League



Spirit of the past
You have strange feelings about this place -- go to Mick's House after meeting Casey




Hello, world!
install your first software -- install your first software ie.from Emmit/Bobo/Silver, etc



Little hacker
use backdoors, get Bobo to hack the fight result -- after getting some reputation with Bobo's Gang, Little Bobo will offer you his service at the Abandoned House. Accepting it will unlock this achievement.


get promoted at either job (Club Street/ Junkyard/ Bobo's Farm)

Employee of the week
Get your first promotion at work. Keep going!


Employee of the month
You have achieved serious success in your work! Keep up the good work!


Employee of the year
Become the most valuable employee. What to do next?





Law student
According to chapter 3, paragraph 5, article 21, you're awesome -- start learning the city's law at police station



Handyman
renovate the gym



It's good to be alive
Feels like something came out of the Graveyard. Spooky. -- summon Mick after getting the hardware from Emmit and getting the passcode from Casey at the sewer



Own four walls
have your own place to live -- after you deliver Emmit's chip to Night Club manager (Night Club is next to Noodle partime location) You deliver the holo device to Mick's office and becomes a trainer of the gym, which becomes your new home.




Now you are worthy
When you have something useful for me, you will be worthy -- when you try to access the door behind the monk under the bridge, some funny event unfold, give him two airpods (both left and right airpods can be found when you explore the sewers as interactable box) if you open your sewer map and some path are blocked, be sure to level up your job in factory, farm, and noodleshop to open those paths.



Champion – starter pack
Now you are the best among the worst! New horizons are waiting for you -- be rank 1 at Silver League

in Chapter 2, there are some big changes..
notably you have 2 new work that will take your daytime: gym and police work.
usually each work will have 1 day interval, and the tournament at the third day, so it will be hard to manage your time for training to raise your stat.

One viable strat is droping either job. I skipped 3 days of police work and got suspended (not fired) and can resume the work again afterward, with the work bar progress still intact! This is especially helpful if you haven't finished maxing your base job (junkyard/noodle/slime farm). This is assuming you want to experience the story of both, but you can just focus on one and completely skip the other to progress.

some tips:

• if you have a hard time, there are some helpful NPC under the bridge, don't hesitate to buy 2 medium booster or one big booster to amp up your stat temporarily (boosting your stat also unlocks the moveset requirement from the skilltree, thank you @sbeve for the tips)
  
• the spoon kid under the bridge can help you save time, and/or keep some of your lower stat low.
  
  Trading one skill point of any skill will only restore up to that skill's value -1.
  For instance: 8 strength, 6 agility, 3 out of13 stamina, you're missing 10 tonus
  trading in strength will restore 7 points, strength will be reduced to 7, and your stamina is now 10 out of 13
  trading in agility will only restore 5 points, agility will be reduced to 5, and your stamina is now 8 out of 13
  (credits to r.wardy)
  
  that one lost stat can be regained superfast if the stat is on the lower side (under 10) using your gym equipment
  
• For each path, you should find 2 more styles: one focusing on enemy that blocks, and one that focused on enemy that dodge. Definitely pay attention and use this to your advantage!
  
• if you run out of energy, remove some attacking moves at the end of the round, since it will let your character regain energy, just put some dodge/block in the defence stance (preferably the one that sucks action points not energy), and remove the attack modifier that takes energy too.
  
• Casey will start having like 2 slices of pizza leftover daily after some event, so take advantage of this!
  
• Do not hesitate to use bus, since your work now has tight time limits, in the earlier stages, you cannot even reach the second milestone for 100$, so after you meet your quota, feel free to just do another thing. Don't forget the software to lower bus rate, and if you can get the free ticket from the courier, that is a huge timesaver
  
• Use Neurotrainer to raise your core stat (highest one), and train manually at night to recover your tonus.
  
• If you find it hard to use neurotrainer at daytime because of the timings, you can still train traditionally at night, but don't install/remove Silver's software that amps neurotraining result and lower traditional training, and instead install Emil's manual training software instead.

No blades in the gym
You have proven yourself in the police. You will be better now at paperwork.-- after about 25% progress bar at police station, you will get a case to Silver gym. This achievement will be unlocked after the case is over.



Get out of my apartment!
You have proven yourself in the police. You will be better now in patrol. -- after halfway bar, you get another case to your apartment. You'll get this achievement and the perk to be more effective on patrol.



The last bell ring
You have proven yourself in the police. You will be better in relationship from colleagues. -- at around 75%bar of police duty, you get another case. After fighting a drunkard at nighclub this achievement and the perk willunlock.



Escaped from a big trouble
You helped that poor guy, he is your student now. -- after about 25% work progress at gym, Mick will tell You to help a guy. You'll fight 3 opponent including (cough) Majima lookalike. after some cutscene, this achievement will pop up



Guiding on the right path
You have inspired a young one, he is your student now. -- part of story, after around 50% gym progress, Mick will ask you to help another person. Prepare for another 3 person fight



Responsible approach
You have convinced a doubting one, he is your student now.-- another pupil, saved by fighting a single drunkard




Mysterious voice
You don't know her, but she sounds so alluring and confident. -- after some matches in second league, there will be a cutscene starting with Uncle Barry and ending with the mysterious girl captured by FBI.



Legal courier
You have defended your right to be a legal courier -- in second league, after some victory, you will get a celebration donut, which you must get from beating the courier. beating him gives this achievement.



Underground dwellers
fight tinfoil guy at sewer -- after the finfoils try to rob Apu, you will chase them to the sewer. After some cutscene about the fake resistance, you'll get this achievement.



Seashell hunter
You have found all the lost shells. Apu is happy. -- after fake resistance incident you will be tasked by Apu to hunt the toilet pap-- seashells.

first batch location:
- below bridge
- bridge
- abandoned house
- club street
- inside the nightclub
- bobo's farm

second batch:
- Casey's hideout in sewer
- below bridge (i think this is bugged)
- junkyard
- dreamlab
- tower
- silver gym, neurotrainer room
- Henry's house (thanks to @Kirbo for fixing this)



in Chapter 2, when you almost maxed the workbar at police or gym, when you take a rest, there''s a chance your mom will call you and ask you for more meds, after some going back and forth to Apu and her, she will be unconcious..

Deal with life
Your mom took care of you. Now it's up to you to take care of her! -- unlocked after the cutscene of MC's mother unconcious in hospital



Champion – no way back
You won the Second Division of the Pro League! The absolute championship -- beat Chappie

Congrats on reaching chapter 3, if you build a decent build, there should be no problem to cruise chapter 3. Stat building over the 25s takes a long time.. so you may want to try to alternate to another style using your leftover GPP just to have fun, or you can stick through if you want to unlock the whole skill tree.

You can farm GPP by hacking the matches even if you fight lower rank opponent for money, you will still get around 100-200 points besides the money.. Though the cap is around 9 thousand for division one, which i think is just enough for maxing out one skill tree. In my playthrough i went agi route in chapter 1 and 2, and in chapter 3 for the fun, i opened the str route, i got to around the 25s in the skill tree for both, which is enough to beat any opponent to endgame..

Just remember to capitalize on your opponent weakness, ie:
> if your opponent is low on energy, try to use moves that drain his energy, he will lose tons of hp when he is down from exhaustion.
> if your opponent is low on initiative, use moves that drain initiative, making him a punching bag.
> your opponent cannot dodge if he is pushed to the rope, capitalize on some moves that pushes through




The die is cast
You made your choice, and it was definitely worth it. -- pick either become a detective (taking sergeant's offer) or a sensei (taking Mick's offer) and after your work bar is maxed, you get a cutscene and this achievement.


Mom got better
You happy to see mother’s smile again… -- after either becoming a sensei or detective, your hospital fee is paid for. Player's mom is cured and this achievement will unlock.



Poisoned fighter
It's your lucky day that you're not him. -- upon reaching about rank 9 in Division 1, you'll fight Claudius (previously named "Some Dude"), and a cutscene will unfold, giving you this achievement. credits to @miravol for the updated name




Undercover robot
THE MACHINES ROSE FROM THE ASHES OF THE NUCLEAR FIRE…, ahem, forget it. -- around rank 6 in First League, you can fight "Undercover Robot" and after some cutscene, this achievement will unlock



Anyone can resist
Slimes can rise too. Why not? -- there will be an event where Apu dissapear from his shop. After meeting him and his friends in sewer, you will get this achievement.



Gang wrangler
You proved you're not to be messed with. --Be a dragon like Kazuma Kiryu!! lol, actually at 25% Progress of your new Career, you'll be tasked to defeat him. If you suceed, this achievement will pop up.


Problems of cyborgs
Your leather fist is stronger than his metal things. -- at 50% progress an event to beat a cyborg at Abandoned House will occur to receive this achievement.



Trap disarmed
You finally put an end to all the unpleasant brutality. The city is saved! -- at 75% work progress and event at sewer will occur, beat the wrestler to get this achievement.



Careerist
You have reached significant heights in your work, your mother can be proud of you! -- unlocked after you have full bar in your work progress as sensei/detective



Absolute Champion!
You’re the most powerful fighter now, right? -- beat Jax

after beating Jax, you will lose access to the tournament, so you can't farm gpp from tournaments anymore.
Also you will lose access to some of the previous achievement, ie. progressing your job at gym/police station will have you stuck. ie. i cannot progress getting a disciple at old house because lil bobo isn't there anymore, and i can't even trigger the Apu dissapearance event.
update (3 aug) 1.002 mention that this shouldn't be a problem anymore.



Not little hacker
You don't know how it happened, but somehow you deal with things like that. -- after you beat Jax, you will get a mission to make a scanner device with the help of Carla, after you finished the device in your garage, this achievement will pop up.


Keep nature safe
Now you know where the slimes came from. -- with the Hacking Device, talk to Big Bobo



Family comes first
Let it be good, do what you should. -- with the Hacking Device, talk to Koji- er, Delivery Manager



Better cooking at home
You found out what was with that poisoned food.-- with the Hacking Device, talk to Yakuza Boss



Silver’s past
Did Silver tell you something that wasn't a lie? -- with the Hacking Device, talk to Silver



After reporting your findings with the Hacking Device to uncle Barry, cutscenes will unfold, and you will get these achievements below..

Key memories
You've done your own investigation and now you know how things work in this city.



The lonesome road
You took your first trip outside the Town!



The heart of the Resistance
This place keeps a lot of answers.



Another world
Don't stay here for long, otherwise your eyes will get tired.



There is a pseudo selection for the ending, one for a good of all, and one for a selfish one. I'd suggest picking the bad one, as you get to see some extra cutscenes and you don't even need to re-fight the whole thing again.

The only right decision
Your dad is so proud of you.

First defeat
Lose one time



Your own way
Now you fight your own way - master the path of Lazy Bear/ Dancing Monkey/ Angry Tortoise (need either stat lvl15 & 10 gpp)



Extreme neuropower!
extreme neurotraining intake damages your brain. -- use the extreme neurotrainer at Silver Gym



Fitness professional
Achieve any stat to 5


Workout professional
Achieve any stat to 15 value


GYM professional
Achieve any stat to 30 value




Fighting is cool
win 10 times


Fight for life
win 25 times


Fight is life
win 50 times