Rotozoomer
The effect that rotates and zooms a texture in real time — the early-90s way to show you had fixed-point maths down.
A rotozoomer rotates and zooms a texture in real time: for every pixel on screen the effect works out which pixel of the source image to sample, using a rotation matrix and a scale factor. Done naively that is expensive, but because the steps between neighbouring pixels are constant, you can accumulate dx and dy per scanline and drop the multiplications — all in fixed-point arithmetic.
The effect became shorthand for the early-1990s PC scene, not least after Future Crew's Second Reality (1993). It was also a forerunner of the texture mapping that soon became standard in 3D games. A rotozoomer on a tiled texture that cycled its palette at the same time was long regarded as proof that a coder knew their maths.