When you encounter a mission to revive a race, stop when you get to the final step before colonizing the planet , then save and exit to game title screen and alt tab out. ( you can get the race revival missions to trigger by destroying a few races in a sector, one of the remaining races will give you the mission to revive an random race to be its ally , it might be more common if one race is at war with many others)

You can try to trigger the mission to revive a race by killing off a few races and leaving a few who are still on good terms with you (pick the ones everyone else hates like brunt or fringe or aggressive young races)

This next part no longer works because the game doesn't keep track of you unlocking the races each time.

Next navigate to C:\Users\YourUserName\AppData\Local\DroxOperative2\User\chars
and sort files by recently modified , the 7 most recent should be:

• x.map

• x.wld

• x.pwl

• Global.sav

• Global.sts

• x.chr

• x.his

(x will be different depending on your character and sector names)

Copy and paste these files to a different folder on your desktop then tab back into the game and complete the quest by colonizing the planet. The race that revives can be a random Young race, a normal race or one of the subclasses of the normal races.
Sometimes the race will die instantly because the planet isnt habitable for them (water species on a desert planet ect ect) if you unlock a subrace this way it will still count even if they die instantly.

Either way save and exit back to title screen and alt tab out of the game again. Then copy the old save files from the folder on your desktop and paste them back into the drox operative chars folder allowing them to overwrite and replace.
Now you can tab back into the game and complete the race revive quest again , you wont lose any subraces you unlock this way even if you revert to the old saves and you can do it repeatedly until they are all unlocked.

Well this method was patched out or perhaps the way the game saves the unlocks just changed , either way this no longer works but the "hard way" still works just fine and is more fun unless you are in a rush to unlock.

I'm not sure what triggers most of the rebellions, i play on "very fast pace" scenario setting so most planets are afflicted with genius paranoia , radiation leaks , civil unrest ect. Some systems will have modifiers like lots of mutants spawning in this sector , which seems to help.

Forcing a rebellion using propaganda usually resulted in generic rebels for me (for example Shadow rebels), *these are now a new subclass see note below*, i had more luck just allowing things like sabotaging to cause instability or allowing genius paranoia to linger while keeping the race alive until the special rebels show up (for instance mutants or clone subrace). Leave a comment if there's a mistake or you found the methods to unlock that I've missed.

*note on "rebels" These are the new subraces for all classes, simply support a rebellion by spreading propaganda on planets for the major races (human , dryad , hive ect,) until the riots turn into civil war , then look for the red circle with a question mark on the map screen of the area you just spread propaganda in. This is the location of the rebel ship, go to them and complete their quest and it might cause the rebels to "split the empire". You might need to complete multiple rebel quests and they dont always succeed in causing the empire to split.
Human subraces

• Ape: Support genetically modified ape rebellion on a human planet (don't bring supplies to suppress the mutants just ignore them until a rebellion starts then support the rebels. make sure they are ape rebels and not generic rebels)
  
• A.I. : You will see a quest related to rogue A.I,, instead of helping to get rid of the A.I. look for a rebel ship on the map , perhaps related to computer virus on planet or genius paranoia
  
• Justice : Human will ask you to suppress rebels clamoring for justice ; instead support the rebels
  
• Kyiv : Second Rebel faction , Same as before Human will ask you to suppress rebels clamoring for justice ; instead support the rebels *Credit to " Agro, Died, Etc " for mentioning this new unlock*
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

Dryad subraces

• Mutant : Race description mentions radiation leak so sabotaging a planet might work then support mutant rebels or wait for a galaxy that has "more mutants" as a map modifier
  
• Talon : Monster race not playable
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

Utopian subraces

• Cyborg : Only found this by resurrect a race quest but might be related to genius paranoia
  
• Legion : Monster race
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

Fringe subraces

• Ultimate Weapon : Resurrect a race mission , perhaps genius paranoia or "help with research" can trigger them.
  
• Genetic Soldier : Support a rebellion of genetically modified citizens rebels

Hive subraces

• Genetic : Support genetically modified citizens rebels
  
• Overlord : Monster race
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

Drakk subraces

• Clone : Support clone rebels , might be triggered by genius paranoia
  
• Drakk Cortex Hybrid : Resurrect a race mission , perhaps related to having drakk and cortex be allied or at war with each other
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

Lithosoid subraces

• Asexual : Resurrect a race mission or spread propaganda to start civil war
  
• Xenophobia : Don't cure xenophobia on lithosoid , eventually rebels will show up (monster raids or boss monsters can sometimes spread diseases like xenophobia, galactic flu ect)
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

Cortex subraces

• Telepath : Support rebels , perhaps caused by genius paranoia
  
• Cortex Brunt Hybrid : Perhaps related to genius paranoia or having the two races allied or at war
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

Shadow Subraces

• Zombie : Don't cure zombie plague on shadow planets
  
• Paranoia : Don't cure genius paranoia on shadow planets
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

Brunt Subraces

• Pirate : Ignore missions mentioning piracy, or even weaken a planet and lure the pirate into attacking, i unlocked this race when a pirate attacked a planet.
  
• Barbarianism : Don't cure insanity on brute planets
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

Scavenger Subraces

• Reaper : Don't cure insanity on scavenger planets
  
• Infection : Don't cure galactic flu on scavenger planets
  
• Generic Rebels Spread propaganda until civil war starts then look for rebel ships and complete their quests

You can unlock the young races (even the primitive races) but you need to help them out a bit first rather than starting a rebellion like with subraces.

First they need to be in space age before you get the "win" condition to have any chance of unlocking them , also they need to actually survive until the end so keep that in mind and choose a win condition that won't conflict with that.

It might take multiple maps before they advance far enough , if you stay in the same "sector" the game remembers which young races exist and you should be able to advance them over time , as long as they stay alive.

You can help them advance their tech level by buying things from them (gives them money) , Not selling to them (you might think selling them high tech gear would be good but they don't gain tech from it and since they pay you for it they lose money) , helping them with missions , raising their tech directly with Tech Items (you can find tech blueprints and give it to them)

There might also be missions where they ask you to steal something using espionage , I'm not sure if they gain the tech from the espionage but it's worth a shot.

If you get the young race you want and keep it alive until the end of the mission there is a good chance it will Emerge in the sector , which means in your next mission they might show up again as long as you don't start a brand new section and they will have kept the progress you made raising them up and give you more chances to unlock them.

To check if you have unlocked the young race click play on the main menu , click "new ship" and at the bottom below the regular races will be a section for "Young Races" with a drop down box , in here you can find the young races you have encountered (and kept alive until winning that map)