This mod introduces a concept of "Research Power" (RP in short), which determines how many research slots every nation in the world gets.
Requirements for unlocking each research slot:
1: 0 RP
2: 0 RP
3: 50 RP
4: 200 RP
5: 400 RP
6: 700 RP
7: 1 00 RP
8: 1 500 RP
9: 2 000 RP
10: 3 000 RP
RP is generated by civilian & military factories, as well as naval dockyards.
I also introduced something I call "Easy Research Slots", which are slots that the nation would have otherwise (starting slots + gained through national focuses), and have their RP requirement lowered to 60%, so getting to original 5 (or 6 in some rare cases) is much easier than it would be. So be sure to not ignore those focuses that give research slot!
While certainly there is still a lot of balancing to be done, both in terms of RP requirements, as well as how much of it each building generates, I am satisfied with the current version of this mod so I decided to share it already.