Yeah. Like the DOOM engine, but without walls, cellings (well, you can simulate them doing two mode-7 "windows" (I name the mode-7 sectors on the screen as windows) at the same time) and slopes. Only a floor and sprites on it.
Hovewer, it has an advantage: the level space is infinite (in the language that I use is possible to repeat the floor as a tile too).
AN EDIT THAT REALLY IS ANOTHER POST: Nevermind. I found the method for do a simple raycasting (but VERY simple, because different heights are missing, damn!!!)... Just, I'm searching yet, but at the moment, no more advanced 3D engines are needed. ;)