Morituri te Salutant
Complete the game with Combat Death turned on.

• Self-explanatory. Since you are going to need to do 2 runs. It is advisable to do this achievement with Iron Man mode at lowest difficulty setting. It is doable at hardest difficulty but there is no need for that.

Ego Sum Spartacus!
Complete the game in Iron Man mode.

• Complete the game in Iron Man mode. Since you are going to need to do 2 runs. It is advisable to do this achievement with Combat Death mode at lowest difficulty setting. It is doable at hardest difficulty but there is no need for that. Also, you can use your insane save files for other achievements easily, if you do a separate run with the insane difficulty.

Julius Caesar
Finish the game on Medium difficulty or higher.

• Self-explanatory.

Pompeius Magnus
Finish the game on Hard difficulty or higher.

• Self-explanatory.

Licinius Crassus
Finish the game on Insane difficulty.

• Self-explanatory.

Patronus
Meet Consul Lucius Licinius Lucullus.

• Story Achievement, cannot be missed.

Legatus Legionis
Gain command of Legio Victrix.

• Story Achievement, cannot be missed.

Para Bellum
If you want peace, you should prepare for war.

• Story Achievement, cannot be missed.

Pax Romana
Restore all of Asia Minor to Roman control.

• Self-explanatory. You need to follow the quest line and conquer all of Asia Minor.

Prima Facie
Recruit Deianeira to your party.

• It is a part of “Morituri te Salutant” mission which is a storyline mission. You will receive this mission, after advancing at Asia Minor. At the end of the mission, just accept her to join your legion.

Citius Altius Fortius
Complete The Olympian.

• This is your first side mission for a companion. Take Bestia and Syneros with you, then talk to Pigres at Temple of Apollon to start the mission. Accept Bestia to be Syneros' champion (Bestia will be injured). First part of the mission is completed. The second part starts at your camp. Once you go to your camp, save the game and talk to Diodoros near the entrance of your camp. Let them have a “riddle off”. There will be 3 riddles in total. The last one is fixed but other two can vary from six riddles. You can use Logos for first two riddles and Pathos for the last one to find the answer. Or you can just answer the questions which you have 2/3 of chance to give the correct answer. Be careful though, you need to select the option which cannot be the answer, after that Syneros will find the answer.
  
• You can check this guide for riddles' answers:
  https://www.ggrecon.com/guides/expeditions-rome-olympian-riddles-answers/

Cedere Nescio
Fight an army of 300,000 and lose.

• Self-explanatory. You can attack the army with 300,000 power and lose. It is not game over but save and load would be helpful.

Ophidia In Herba
Attempt to poison Mithridates.

• This one is from “Hostage Exchange” mission. You are going to need Pathos to be able to poison the wine. Before going to negotiations, while talking with your companions and Lucullus choose the poison option (This option is a must). After that you need to choose the Pathos option with Laomedon (After talking with Mithridates for the first time.).

Miserere Nobis
Side with Theophilus at Mysia.

• Self-explanatory. Side with Theophilus at Temple of Apollon.

Romani Ite Domum
Fight and kill Albinus in Gaul.

• This achievement actually has 3 parts in 3 chapters. I wanted to put it here, because it starts at chapter 1. First part is “Romani Ite Domum” mission. Do not kill Albinus, since we are going to need him and to be sure, send him to the legion for punishment. Second part is at chapter 2's “Contempt of Court” mission. Again, same logic but after contacted by the woman about Albinus, do not leave the area. Last part is at Chapter 3's “Respice Finem” mission. You can kill him to get the achievement here.

De Legibus
Learn a second rhetorical technique from Cicero.

• You can talk to Cicero, after returning to your home. It is not the first encounter which is the one at the party. After it says 5 years passed and before going to Africa, you can talk to him. You need to talk to him at Senate, he is at the right side.

Regina Aegypti
Meet the rightful Queen of Egypt.

• Story Achievement, cannot be missed.

Carthago Delenda Est
Furthermore, I consider that Nasamones must be conquered.

• Story Achievement, cannot be missed.

XVII
Learn the ominous meaning of The Number of Death.

• Directly part of "The Number of Death" mission. After conquering some of Africa, there will be a random encounter which starts this mission. Proceed with the mission and complete it for the achievement.

Ab Antiquo
Reforge Tutankhamon's dagger.

• This achievement is related to "The Number of Death" mission which is a side mission. Proceed with this mission, until going into the pyramid. After clearing the pyramid, there will be a breakable wall. Break the wall and take the Meteorite Blade. This will start another side mission for reforging the dagger. Go to Memphis and talk to the smith. There will be a new place at the map. Go there and take the schematics. Lastly, forge the dagger.

Lex Talionis
The Law demands an eye for an eye.

• You need to conquer every region for this achievement. Beware that this achievement can be missed if you complete the main objective before conquering Africa.

Arcana Imperii
Become the Proconsul of Egypt.

• I am not sure about it but being the male character is advised, since there is a chance that you cannot become Proconsul with female character. Close to the end of the Act 2, you need make a choice between Cleopatra and Lunja (After Ptolemy is dead). Kill Cleopatra for the achievement. At Rome, you will go to the senate for being the proconsul. Ethos and Pathos will be beneficial here but if you do not have that you need to choose carefully (like choosing talking about the defeat of Lurco).

Pater Familas
Marry Cato.

• You need to be a female to be able to marry Cato. This option will be present at the end of chapter 2.

Post Coitum
Sleep with Cleopatra.

• You need to be a male to be able to sleep with Cleopatra. After saving her choose the romance option at the Lucullus' villa. Then, talk to her again and choose the option about god to be able to pick the romance option. Finish her side mission with quality carpet while ordering a new carpet (I am not sure if it is necessary). Also, protect her during Act 2. She will visit you at the end of Act 2 at your villa. You can select one, one, two, three, two, one, two, one, two, one, and then the final romance option to sleep with her.
  
• You can check this romance guide for more information:
  https://www.ggrecon.com/guides/expeditions-rome-romance-guide-every-character-you-can-romance/

Familia Supra Omnia
Complete Family Reunion.

• This is Bestia's personal quest. Speak Gulussa at Court of Heaven and choose the "That serva. With the peculiar birthmark" option. After that you can buy the slave or kill the man. Talk to Bestia at camp and choose between killing the sister or sparing her life. Sparing her life ends the quest right away and gives Bestia Agreeable trait. Killing her gives Bestia Scout trait and he goes for a couple days (you get the achievement after that).

Memento Mori
Complete Afterlife Travel Guide. Translation: reminder of mortality.

• Speak to Aksil at Court of Heaven to start this mission. This is a pretty straightforward mission, just complete the Afterlife and then talk to Aksil to conclude it.

Audi, Vide, Tace
Complete The Golden Wolf.

• Speak to Lunja, after the battle in Strange Alliances. She will mark Sandblown Ruins, go there and finish the combat. You can return and finish the mission, after that.

Legio Patria Nostra
Complete The Tax Collectors.

• You can find this mission at Memphis. Talk to Iglider at northeastern side of the map to start the mission. Also talk with the local leader and offer compensation. After that, talk with Iglider and learn about the stash. Talk to Egnatius Naso at legion for punishment to conclude the mission.

In Loco Parentis
Complete Damsels in Distress.

• This is Caeso's personal quest. Speak with Caeso at Rome, after returning from Africa. Speak to Vipsanius at Vipsanius Villa. You can either take his offer or kill him to finish the mission.

Collige Virgo Rosas
Complete Marticide.

• This is Calida's personal quest. Speak with Cicero and meet with Calida at the streets. If you are male and romanced her, you can marry her to conclude the mission (she did not accept my offer for some reason though) or you can go to the court and complete the mission.

Pede Poena Claudo
Complete The Third Man.

• This is Deianeira's personal quest. Talk to her at Rome and travel to Collegium Bacchus. Complete the area and leave after you have done. That will be all for this mission.

Bellum Gallicum
Begin the war in Gaul.

• Story Achievement, cannot be missed.

Sanguinem Sacrificium
The gods demand a tribute in blood.

• During The "End of the Aedui" story mission, you will be required to make a human sacrifice. If you talk to Tinus, after talking to Divitiacus, you will learn that there is another solution which requires for you to sacrifice one of your eyes. You are going to need a sickle from Ambiorix. Once you have collected it, save and sacrifice your eye for the achievement. I used Iurca from Arena of Gallia after reloading, since sacrificing an eye gives disadvantage.

Magnus Opus
Complete A Menhir for Divitiacus.

• Talk to Tinus at High Place for this mission. After that, go to the marked place and new event will occur near it. You can choose between paying for the menhir or doing something for the merchants. The second option will lead to a hunt which you can send Calida. Lastly, go talk to Tinus and complete the mission.

Veni, Vidi, Vici
You came, you saw, and you have conquered.

• Story Achievement, cannot be missed. Contrary to Act 2, you do not need to conquer all of the areas, completing "The Conquest of Gaul" mission will be enough.

The achievements below are ending achievements.

Quinctius Cincinnatus
Retire to your farm or remain active in Roman politics.

• When you return to Rome at the end of Act 3, choose to disband your legion; then defeat Lurco at senate. Do not attack him at the hostage situation. You can choose these options at the end.

Marcus Antonius
Willingly exile yourself from Rome.

• When you return to Rome at the end of Act 3, choose to disband your legion; then defeat Lurco at senate. Attack him at the hostage situation and choose the exile option at the prison.
  
• OR
  
• Cross the Rubicon, defeat Lurco and choose the exile option at the end.

Junius Brutus
Sacrifice your life for your friends.

• When you return to Rome at the end of Act 3, choose to disband your legion; then defeat Lurco at senate. Attack him at the hostage situation and choose to stay at prison option.
  
• OR
  
• Cross the Rubicon, defeat Lurco and choose the surrender option at the end.

Gaius Octavius
Become Dictator for life.

• When you return to Rome at the end of Act 3, choose to cross the Rubicon with your legion; defeat Lurco and crown yourself.

Amor Vincit Omnia
Complete a romance.

• Caeso, Calida, Deianeira and Bestia are the companion romance options. You can just pick the romance options whenever it is possible. Beware that there are no homosexual romance options. Other than companions, you can romance Cleopatra for men and Cato for women. There are separate achievements for these two which you can check under Act 2.

Abundans Cautela Non Nocet
Finish a combat encounter without taking any health damage.

• It is actually pretty easy. You can do this achievement at the fire encounters. The best option would be Temple of Apollon at Act 1. There will be a fire encounter at the west side which you can complete easily.

Nil Per Os
Complete an encounter while both starving and dehydrated.

• My advice would be using the before mentioned fire encounter for this one also. Save the game and sell all of the food. Run around the map without using wells or going around the legion. Once you are both starving and dehydrated, go to the mentioned encounter and get this achievement.

Causa Mortis
Kill/Incapacitate an enemy by cutting of all limbs

• You need to get critical hits to low HP enemies for this achievement which you will easily get while playing the game.

Damnum Absque Injuria
Incapacitate an enemy with the damage from Rebuke.

• You can get "Rebuke" and damage for "Rebuke" for Sagittarius class. However, this achievement was bugged for me. For some reason, it did not apply for many times and it did for some reason after a while.

Morior Invictus
Incapacitate an enemy shieldbearer without dealing damage to their shield

• This achievement is a bit problematic. Enemy should not be panicked, stunned or something like that for some reason. Do not damage the shield in any way. You can burn him, until he/she is near death. However, do not kill him/her with fire, since it will be an environmental kill. Use a Triarius with shield ignoring skill.

Tuebor
Incapacitate an enemy with an Attack of Opportunity.

• It is pretty easy and you should get it naturally. If not, you can use "Route" or "Taunt" skills.

Accipe Hoc
Incapacitate 3 or more units with one catapult strike.

• This one was a pain in the ass for me at hard difficulty, since there is a one turn delay and random fall. The best place can be the last act but if you can do it before that, it is great.

Ante Omnia Armari
Start a figth with every weapon type equipped with every type of weapon in the game.

• Weapons are swords, daggers, shields, pikes, spears, staffs, bows, fists and scissors. Every character has two loadout options for weapons and you can take 6 people at your party which means you are able to have 12 options. Staff, spear, bow and unarmed should take one spot each. Double dagger, dagger and sword, dagger and shield, dagger and pike, pike and shield, sword and shield, scissors and sword, scissors and pike should be enough for this achievement. If not change, the spear or staff with scissors and dagger. Since scissors added later, there is a chance for not needing them.
  
• PLNTRXS says "Need 2 triarius one with staff the other with pike, obviously Synerios is necessary, 1 sagittarius with bow, 1 veles with dagger/sword or dagger/spear, 1 principes with shield and the weapon not used by our veles and one more companion unarmed in both hands" This could be the easier and correct approach.

Mors Tua Vita Mea
Perform a takedown with every type of weapon in the game.

• A bit confusing achievement. You need to perform a takedown, not knockdown or kill which means there should be a cutscene which your character kills the enemy with different weapons. Weapons are swords, daggers, shields, pikes, spears, staffs, bows, fists and scissors. You can just save before takedown and then use another weapon. You can also use your companions for this achievement, thanks to Xelian for this information.
  
• Here is a video for the takedowns:
  https://www.youtube.com/watch?v=7xcMw_YIKqM

♥♥♥ Gladia Et Sale
Shred 10 points of armor from the same character.

• There are couple of enemies for the Insane difficulty. If you are not able to do it at easier playthroughs, you can do it while you are getting the insane difficulty achievement. Pila is a great asset for this achievement.

Per Pedes
Move 42 or more hexes in a single turn

• You are going to need a Veles for this achievement. Learn "Marathon" skill and use this skill in a big map (you can use it once in a combat).

Festina Lente
Perform five or more attacks in a single turn.

• It would be very easy with a Sagittarius who has "Barrage" skill. You can also use quick shot and get "Marksman" from sniper tree for more accuracy. Do not forget to change your bow, after using the first bow. You can use the untrained enemies for this achievement by lowering their HP with other characters or use "Inspire" skill of Triarius (you can use more than one). As a second class, you can use Veles with "Sneak Attack", "Rush", "Shiv" and "Reaper" ability ("Marathon" can help also). Triarius with Destroyer tree is also an option for untrained enemies.

Oderint Dum Metuant
Fully break morale of more than 5 enemies in a single encounter.

• This one is another hard one. You need to break the morale all the way down to the routed status. You can use skills for lowering the morale and kill leaders. Catapults can be used also. I got the achievement, after not disbanding my legion and fighting at Rome. It could be a good place since there will be lots of enemies at the end.

Semper Paratus
Use more than 5 consumables in a single encounter.

• Pretty easy achievement. You can just use the items in the same encounter.

Nec Aspera Terrent
Complete an encounter with 6 people on your team but no Heavy class characters.

• Self-explanatory. You can use the before mentioned fire encounter, if it is too hard for you.

Aut Viam Inveniam Aut Faciam
Unlock every legion battle Stratagem.

• Self-explanatory. Use a praetorian for new stratagem and upgrade the building to last level. Do not forget to check the building for getting new cards.

Iuncta Iuvant
Have character assigned to each outpost assignment at the same time

• Self-explanatory. One person should be enough for hospital.

Ad Altiora Tendo
Construct all Legion outpost buildings

• Self-explanatory. Since you are going for the achievement below, you are going to build each building anyway.

Non Plus Ultra
Fully upgrade all legion outpost buildings

• Self-explanatory. Since you are going to capture everything for other achievements, you will have all of the required resources at Act 3.

♥♥♥ Laude
Become the Champion of Asia Minor.

• Self-explanatory. You can go to the arena at Act 1 and fight until you become the champion. Fights are not that hard and you can rest between the fights.

Magna ♥♥♥ Laude
Become the Champion of Egypt.

• Self-explanatory. You can go to the arena at Act 2 and fight until you become the champion.

Summa ♥♥♥ Laude
Become the Champion of Gallia.

• Self-explanatory. You can go to the arena at Act 3 and fight until you become the champion.

Plaudite Cives
Complete the game as a Gladiator.

• Self-explanatory, just pick the Gladiator class and finish one of the playthroughs.

Circulus Vitiosus
Kill 25 enemies with Retaliation attacks.

• Helmet of the Legend, Hand of Chiron Scissor, Zaririchi's Labrys and Heavy Armor with Armor of the Challenger Charm is a good build for the gladiator, both with high retaliation chance and heal. Since, gladiators are weak early game, I would recommend trying this achievement at Act 3. You should be able to use the training fights for this achievement.

Absit Iniuria
Kill Sebastianos in the amphitheatre before ending the encounter.

• Sebastianos will appear at one of the fights of arena at Act 1. He will be shooting arrows during fight (you will be informed before the fight of course). Use a Sagittarius to kill him and you will get the achievement. You won't have any chance, after finishing the encounter.

Age Quod Agis
Win an arena fight after reaching 80 negative audience approval.

• It is easier than it seems, just use the negative approval actions like skills and items for one fight until you get -80, after that you can kill the enemy. You can use one of the arenas that enemy not attacking you directly, if you do not get close.

Ad Leones
Have one of your characters get incapacitated by a lion.

• You will encounter the lions at arena of Act 2. Save the game and wait until you get incapacitated by a lion. Lions will be present at one of the arena fights at Act 3 also. Thanks to @Narcissistic Cannibal for reminding me that part.

Contra Spem Spero
Win a fight in any arena with only 1 character left standing.

• Again, save the game and while you are near finishing a fight, let the enemy incapacitate your men, until only one of them is left standing. Then finish the enemy. Be careful about the retaliation though.

Peccatum Originale
Cover every hex in the arena with oil, water, caltrops, fire, or scorchmarks.

• This one is a bit troublesome. The best places to try this achievement would be the fight with assassins at Act 1 or the ship fight at Act 3. You need to equip all of your men with usable items, easiest would-be jug.

These are the resources I used and I would appreciate if you check those links and give them a like:

• Riddle Answers for Olympian mission: https://www.ggrecon.com/guides/expeditions-rome-olympian-riddles-answers/
  
• Romance Guide for Cleopatra: https://www.ggrecon.com/guides/expeditions-rome-romance-guide-every-character-you-can-romance/
  
• General Information: https://expeditions-viking.fandom.com/wiki/Expeditions:_Rome
  
• Takedowns: https://www.youtube.com/watch?v=7xcMw_YIKqM
  
• Gladiator Tactics: https://www.reddit.com/r/expeditionsrome/comments/vbi2a0/my_2c_on_builds_in_expeditions_rome/
  
• Thanks to Xelian, Narcissistic Cannibal, PLNTRXS and Zloth for their feedback and pointing out some of the missing parts.

Thank you for checking my guide. If you have any suggestions or if you see any mistakes (information, typo, etc.), please let me know. Have a nice day!