If you have any mods enabled, it will disable your ability to get achievements. If you have a city that you started using mods on, then that city is "dead". Your city must never have the taste of mods if you want achievements. I suggest having a separate city for achievements and naming it something so that you know to disable mods when playing on it.
This one is super easy to get.
1) Build a Police Headquarters or Police Station. (If you already own a Police Headquarters or Police Station, go to step 2)
2) Click on the Police Headquarters or Police Station 100 times in a row.
That's it. Seriously, it's that easy.
Some notes to keep in mind:
- All clicks must be done in a row. If you click off of the Police Headquarters and then keep going, you'll have to start over.
- I'm not sure if this can be done with a Police Station. I personally used the Headquarters. If somebody could confirm, that would be great. Thank you Vargtornyx
- It can be either the normal version or the European version. Mine was European.
- Police Headquarters is 60,000 ₡ with an upkeep of 1,600 ₡ a week.
- Police Station is 1,200 ₡ with an upkeep of 480 ₡ a week.
Happy hunting!