The Res Publica Add-on for Europa Universalis IV has 5 achievements.
Get a ruler of your dynasty on the throne of Poland or the Commonwealth while they are an elective monarchy.
Restore the Danelaw region to Danish rule, and make it Danish culture.
Have a 75% Trade share in both the Alexandria and Constantinople nodes as Venice, owning less than 10 cities.
Get Orangists in power with 100% Republican Tradition, and owning a province in China.
As Poland, become an absolutist monarchy, abolishing the Sejm.