I am those types of people that prefer smaller huds depending on how big it is, so this is a hud that I can see myself using.
This is a basic fullscreen HUD for the original Classic Marathon. It also works with TROJAN. It is very minimalist, see the screenshots for details.
Software mode works but the square motion sensor will not be clipped out.
All three HUD sizes are supported, but the plugin will not cause the HUD to cover too much of weapons. Basically, Double doesn't work until 2k, and Largest isn't really useful until 4K.
To install, copy this into the Plugins directory in your Classic Marathon install.