All these acheivements will be completed automatically by following the main storyline

Baby Steps - got your first level up
Betrayer's Child After All - Finished Liannon
Prisson Break - escaped the Grey Keep with a new ally
Lord of Mulandir - Claimed Mulandir as your base of operations
Point of No Return - Reached hero party level 20 in the campaign
History has its eyes on you - The fate of Nortander lies in your hands
The End - Beat the Spellforce 3 Campaign

These achievements require you to do some side quests you might not need to for the main story.

Explanation: As you open the door to Mulandir, there should be a wolf walking around the area nearby. Talk to him after opening the door, and the shapeshifting Orc will give you a quest to recruit the orcs.

Explanation: Help the elves in the Woods to the North-west of the map. This quest should trigger automatically once you gain control of Mulandir.

Explanation: Help the woman you meet in Farlorn until she takes you to Everlight city, then complete the quest by talking to the mayor.

Explanation: When you return to Farlorn immediately after taking Mulandir, save all the refugees without letting any of them die during the escort section. (Credit to Istasior)

Explanation: While helping the humans, after saving the refugees you'll end up back in Iskander Wilds. During the quest, destroy all Nortander forces on the map by taking their castle.

Explanation: Occurs during the main quest. While talking with the aristocrat that became a beggar give him 60 gold instead of 30. Dialogue choice.

Explanation: The second time you can return to Aonir's Blade after the plot twist, some mages will offer you a side quest named "In the name of Knowledge" where you must complete a ritual on the right side of the map.

Explanation: Does NOT require you to buy schematics. All you have to do is complete the second Orc faction quest after the Plot Twist

Explanation: Does NOT require you to buy schematics. All you have to do is complete the second Human faction quest after the Plot Twist

Explanation: Does NOT require you to buy schematics. All you have to do is complete the second Elf Faction quest after the Plot Twist

Explanation: Bring the Deserter to the Deathmen the first time you go to Aonir's Blade

Explanation: Bring the Deserter to the Iron Falcons the first time you go to Aonir's Blade (Credit to Wojtek)

Explanation: In the late game you will be told about a dragon in the nearby oasis. Go to the oasis and talk to it and click all the dialogue options asking not to fight. The dragon will give you a quest to close 3 portals in The Eye map. Do so then return to the dragon.

Explanation: In the late game you will be told about a dragon in the nearby oasis. Go to the oasis and kill it.

Explanation: Complete the quest for the Gobling king on the way to Mulandir, then feed him 115 goblin meat. A recent patch introduced a trader in everlight that will sell 50 goblin meat.

Explanation: you can get it at the Unknown Island by visiting a Temple for the Quest "Forgotten Knowledge" during a second visit after you recieve the dragon quest. (Credit to Wojtek and Yimbo)

Explanation: During the prison escape talk Alistair into letting you free. (more details coming)

Explanation: on the east side of Everlight there is a woman standing next to a gravestone. Talk to her.

Explanation: Option from the Main Menu

Explanation: No longer bugged

Explanation: No longer bugged

Explanation: Currently appears impossible since SPOILER...........no one has been able to convince Isgrimm to stay your companion after breaking the runestone........ End SPOILER (bugged)

Explanation: You need to recruit Yria, Isgrimm, Rohen, Gor, Ianna, Undergast, Uram and Arandir as playable characters. Used to be a bugged achievement, but currently appears fixed. Credit to Anja_Nowa

Explanation: I'm relatively sure the max level is 30. Just keep grinding or play through on Circle mage difficulty.

Explanation: Mute the music slider in options (Credit to Derotan)

Explanation: Die to a spider. Confirmed possible on circle mage difficulty when you fight the lone spider before breaking out of your cell, was unable to trigger by dying to other spiders. (Credit to Derotan, Confirmed by ByGN99)

Explanation: Save all 5 prisoners during your escape from the prison (Credit to Derotan)

Explanation: Click on a worker over and over. seems like it works with all races (human/orc/elf)

Explanation: Your main charactar must die. Used to be bugged but should now be possible. Credit to Anja_Nowa

Explanation: Destroy the orc base on your first journey to Farlorn's Hope without building any additional troops. Credit to Gorwe

It has recently been confirmed that both of these acheivements are possible to get...but require extremely unique circumstances

Explanation: Enter the konami code on your keyboard to spawn a deer that will blow up your party. See the steam guide below for even more details https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2389879640

Explanation: Wear the prisoners clothes from the dungeon at the begining of the game to the very end. Recomended you stay on the easiest difficulty to just grind this out one day. (Still bugged as of October 2020, but you can find a community patch in the forums that can make it achievable)
https://www.moddb.com/games/spellforce-3/downloads/sf3-steam-achivment-fix-they-fit-just-right

Now that the game has undergone several patches it appears that all of the achievements are now possible to get. As soon as i get enough time, i'll go through and get a 100% to give you guys an idea of the time required to platinum the game. Have fun finding that doe.

Frankly the thought of grinding out level 40 in the game kind of makes me gag a little, so it might be a while before i can post an approximate platinum time.