When “Duke Nukem 3D” was first released for the PC in 1996, the “3D” in the title was perhaps there to emphasize that this was not the sort of flat-world first-person shooter experience you’d find in a game like “Doom 2.” Rather than just pivoting side to side, you could actually use the mouse to look up and down, setting your sights on an object far below you or flying above you — quite an innovation for the time, as I remember. It made aiming your weapon a little tricker, but it really expanded the world you could explore within the game and made it a lot more fun.
