I found this legendary 3D engine-preview in the AmigaScene archives:

http://www.amigascene.at/amigascene/deutsch/0x0035.html

The game has never been published *sigh*, but it's amazing how fast it works!
Smooth 3D action on a "small" AGA Amiga with at least 4 Megs of FastRAM and a 68030 CPU or higher.

The archive contains 2 versions:
IQ_INT - Integer-Demoversion of the IQ-engine
IQ_FPU - FPU-Demoversion of the IQ-engine

You might want to know the key-settings for the game:

Cursor left: turn left
Cursor right: turn right
Cursor up: move forwards
Cursor down: move backwards

X: jump
CTRL: shoot
ALT + Cursor left/right: slide left/right
Shift + Cursor: Run and fast movements

Left mousebutton: Quit demo

 PERMSSN    UID  GID    PACKED    SIZE  RATIO METHOD CRC     STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]               200520  933584  21.5% -lh5- c282 Jan 16  1980 iq_fpu
[generic]               200109  932308  21.5% -lh5- f1ff Jan 16  1980 iq_int
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total         2 files  400629 1865892  21.5%            Nov  9  2005