The Tetraverse is a universe where all things are completely and forever 4 sided objects. No other shapes exist in this Verse besides tetrahedrons and squares/quadrilaterals. Everything here, including microscopic to sub-atomic levels, are all squares. Circles here are made of squares as well. Physics and other math stuff are all the same, as in, just like in our Universe. The only thing is, it is much, much harder, as there are no circle-related functions and numbers in the equations. Also, pi (the constant) is not known of and any instances will instantaneously round to 4 upon entrance to the Tetraverse.
! Warning !: Once you enter the Tetraverse, you will be immediately transformed into a square creature which still has the features here. In this universe, the fastest way to get to another point is by going up, and over.
In this universe, it impossible to play Tetris normally because some of the pieces are not four sided. The only pieces you would get would be the yellow pieces.