Checking the evidence…Reading the prices…Writing the verdict…
Developers
Paradox Development Studio
4 games in the catalogue.
Crusader Kings IIIBuy on sale$49.99
Regular price; it has been much cheaper
90% positive on Steam
Hearts of Iron IVBuy on sale$49.99
Regular price; it has been much cheaper
90% positive on Steam
StellarisBuy on sale$49.99
Regular price; it has been much cheaper
85% positive on Steam
Victoria 3Buy on sale$49.99
Regular price; it has been much cheaper
71% positive on Steam
Best verdict first. The developer name is taken from the Steam page, so a studio that publishes under two names may appear twice.