Hi! Thanks for the question. Going with squares instead of hexes for LT boils down to squares making programming many, many aspects of the game significantly easier. I did a serious dive into the possibility of doing a different grid system early on and came away with the conclusion that paying the Hex Tax would be a large enough drain on production time to not be worth it – we would have had to cut other features like destructible terrain, the user-facing map editor, or line of sight previews while choosing targets.
In particular, calculating line of sight is extremely non-trivial in a 3D voxel space, and all the best algorithms for doing so have been done with square grids. It would have also made calculating texture bleed between voxels (the effect where some grass can extend across a boundary into a dirt tile) extremely difficult for the engine we have.
I know that most tabletop Lancer games are played on hexes and squares makes diagonals a little funky, but like Airatome1 said, the game was designed to be grid-agnostic (see the Black Witch’s PCP for a fossil of it being originally designed for square grids). Lancer is explicitly not designed to be a simulation, so I’m comfortable letting the rules bend what’s geometrically sound.