Thoughts on Bioshock Infinite

[Kreekakon]

Also, I didn't understand why vigors were there, with there being no explanation for them.

Well first of all the main reason they're in the game is Plasmids/Vigors are mostly a staple of the series.

Plotwise it is explained in a Voxophone recording which displays Jeremiah Fink mentioning a brilliant biologist he's observing through a Tear. This is a nod to either Dr. Yi Suchong or Dr. Brigid Tenenbaum, which in turn would imply that Fink may have drawn inspiration from their work on Plasmids to manufacture his Vigors.