There's a weird kind of parallelism in the design and the premise of the game: Sen is about the period when Western culture began to enter Japan, bringing foreigners in contact with samurai -- and the game is a high-definition 3D version of an SNK classic. So, if we were going to overthink this (and we are), we could see the game's samurai as a metaphor for classic 2D fighters, with the Vikings and other foreign elements representing the unstoppable influence of 3D.
Then they all hit each other with swords.
