TheGod of War 3 saw Kratos bring about the end of the world in the form of a great flood; however, players are mostly left in the dark as to what happened between the flood and the beginning of God of War 4 (also confusingly called God of War). Clearly, the world has not ended completely, and enough time has ed for Kratos to create a new life for himself.
Cory Barlog, the Creative Director of God of War 4: a boat.
God of War Shows Kratos Get to Norse Mythology
The last God of War delved deeply into Norse mythology from the very beginning, abruptly changing the familiar setting fans had enjoyed for the first 3 installments of the series. The world has no serious remnants of damages from the flood in God of War 3, suggesting that a good amount of time has ed. The story begins with Kratos' second wife, Faye, having ed away, leaving Kratos as the sole caretaker of their son, Atreus. The game centers around their journey to spread Faye's ashes from the top of the highest peak in the Nine Realms. Throughout this journey, the characters and players make discoveries of the various mysteries in Norse mythology. It is through these discoveries the details of what happened between God of War 3 and God of War 4 are revealed, including how Kratos may have come to Midgard.
The first hint which players receive about how Kratos got to Midgard in the timeline of the God of War games is through the in-game location Tyr's Bridge. Freya mentions that the structure had been completely submerged for at least 150 years. When players encounter it, the bridge is now clear as a age through Alfheim, standing to reason that at least a century and a half, or more, has ed. In addition, players can find a vase with Kratos' face on it within Tyr's Vault. The existence of the vase stands to reason that Kratos' legend has existed long enough to be ed through mythologies and pantheons, or that Kratos has been in Midgard long enough to forge another legend of renown.
One of the features of God of War 4's world is the amount of water that Kratos, along with Atreus and Mimir, travels across. Seeing as the boat is the primary form of transportation between several regions in the game, it stands to reason that the flood ushered in at the close of GoW3 had lasting impacts on all the pantheons. Check out that scene from the end of God of War 3 below, courtesy of MichaelXboxEvolved on YouTube:
Thankfully, the connections between the Nine Realms and Kratos' existence within them suggest that the flood had a way of better connecting the various territories of different pantheons. Kratos and Atreus discover a carving of Tyr traversing between the realms, with symbols originating from other mythologies littering the corners of the carving, similar to a map. Kratos recognizes the Omega symbol from the Greek alphabet, offering further proof of the physical connection between the various pantheons. This opens the opportunity for God of War to explore other cultures, myths, and legends after God of War: Ragnarök.
If the God of War series has proven anything, it has shown that Kratos is resilient. He has endured grueling combat against gods time and time again, and always claimed victory. The closing of God of War 3 ushered in the supposed "end of the world," but only succeeded in further connecting the territories of the pantheons through the use of water. It remains to be seen how, now that Kratos is in Norse mythology and reaching Ragnarök, this new "end of the world" will affect humanity - but players will be able to find out very soon.
Source: IGN SpoilerCast
