Cities: Skylines

So after a lot of testing I think I've got a setup that always works!.

+Start your city with education boost always on (this increases the budget by 25% but trust me, it's worth it)

+Use a grid layout for your city and make sure to not mix building types. Keep your shops and industry separate from your housing (this comes into play later)

+Make sure to build 2/3 elementary schools for every high school as your city expands. DO NOT BUILD ANY UNIVERSITY BUILDINGS!

+Keep this format untill you reach 100k population, at least 30k eligible for university and you have 1.5 million currency saved

+ SAVE YOUR GAME HERE!

Now for the achievement!
+Pause the timer and remove ALL of your industry and shops (this is why the set-up is important). This will remove all job options for your residents

+Mark the entire city as university campus and place enough dorm buildings for 20k students around any populated areas.At the same time scatter other campus buildings around to increase your campus attractiveness.

+Finally turn on all campus policies.

Once all of this has been done. Unpause the timer and watch the number rise! If this doesn't work, load your save and build up more potential students.

If you have any questions please let me know before negative voting, good luck :)

Dropping a solution in here that I got via Message (summarised), when I asked one of the first who unlocked it (I’ll delete this solution if they make their own):

> Have a population of around 120,000, with over 30,000 eligible for University

> Deactivate School's Out Policy

> Activate Education Boost Policy

> Activate Industry 4.0 Policy

> Delete all generic Universities

> Build a large amount of High Schools (25,000 capacity)

> Let the game idle for 1-2 in-game years

> Once you have over 30,000 students eligible for University, build a Campus with room for 18,000

> Activate all Campus Policies

As soon as you open the Campus you should get 15,000 students right away

I tried a number of the solutions listed without success. My city was mature around 200-230k citizens. I did have the hadron collider so most of my population was well educated - so this is what i did. No need to pause the game at all

1. Delete Hadron collider and any "normal" universities
2. Build campus(s) around your city ensuring you have >20 - 30k of dormitory space and add whichever other campus buildings you have unlocked (I built one of each campus, one in each of the three corners of my city)
3. Turn off all campus buildings
4. Raise all residential taxes to max (25%?) until your population is approximately half of it's starting value
5. Lower residential taxes to 12%
6. Monitor elementary and high school capacity and build additional as required (I was on 35k elementary / 60k high school).
7. When your university eligibility reaches around 30k (it will take around 40-60 minutes) go around and open up all campus buildings
8. Achievement unlocks

This is in addition to CjMAN911's guide:

+ 13 dorms (399 students in each) = 5187. This should cover the 15,000 and 5,000 on campus. Though I've put 15 dorms to be on the safe

+ Once the Commercial and Industry started disappearing I found there was a huge drop in income. I was getting -130k a week. My 3mil was depleting fast. It's worthwhile going around your city and turning off your unique buildings and more expensive parks.

+ In the Budget panel, I dropped everything to 50%. Without the Ind/Com there is a massive decrease in service usage. Though keep an eye on your Infos. For example, my Water and Crime went too low. But this will overall save you a huge amount of money.

+ Power is another issue. Once Ind/Com start disappearing you might find large chunks of the city become detached from the power grid. Keep a birdseye view of the city, monitoring for areas becoming disconnected. Judicious use of pause allowed me to patch up areas. In my first attempt at this, a massive area of housing became abandoned as I wasn't paying attention to it.