To run iortcw on the Raspberry Pi requires SDL2 and at least 128M for GPU memory.

(Under Raspbian, you can set the GPU memory using the raspi-config tool under Advanced Options->Memory Split)

SDL 2.0.8 is required for compatibility with Raspbian stretch.

Download the SDL2 source code (2.0.8 at the time of this writing) from:

http://libsdl.org/release/SDL2-2.0.8.tar.gz

You will need to install the libudev development files for mouse support.
On the Raspbian distro, this is done by running the command:

sudo apt-get install libudev-dev

Unpack the SDL source and go into the source tree and issue the command:

./configure

After that has completed, type:
make

If build completes successfully, type:
sudo make install


At this point you can go into the iortcw source tree and type:
./make-raspberrypi.sh

Output binaries will be located in the 'build' directory, which you can copy
into your RTCW install directory.

You must exit from the desktop (X11) to the command line before launching
iortcw to use hardware OpenGL ES acceleration. You can return to the desktop
using the startx command.