I don't know if this is actually, specifically the case, but when I read the latest CK2 dev diary about having EU4 styled coalitions, it got me to wondering if the PDS devs are making a greater effort to share gameplay mechanics between games when appropriate. There's obviously some antecedent for this - the example that comes to mind is the use of gradual slider changes to adjust country policy in Hearts of Iron II and Europa Universalis II/III. Unfortunately, I'm not experienced enough with Paradox's older games and engines to really say how much was shared in the past, but there are a few examples of what appear to be concepts being side-ported from one game to another:
- The naval combat rework in Victoria II: Heart of Darkness (making naval combat less like EU and more like HOI)
- Upcoming addition of shattered retreats and the aforementioned coalitions from EU4 -> CK2
- Possibly greater emphasis on goods and equipment from V2 -> HOI4
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