All LZDoom features are present (such as fake splitscreen).
Besides the obvious stuff mouse horizontal sensitivity is doubled compared to GZDoom so if you copy your ini from GZDoom 4.5.0 take this into account.
Render cull doesn't work with gl_multithread (GZDoom default).
There's a ram safeguard on windows so disable it with cl_checkram for optimal performance on high memory usage.
GZDoom savegames should be compatible.
Demos and netgames should be too as long as you don't use LZDoom features and enable netcompat.
Besides having compat_oldrandom there's a sv_stricterdoommode cvar to disable some things in compatmode 2.
There's another silly feature to play without doom2 monsters (sv_nodoom2monsters) besides unholy massacre (double monsters), but they are fun.
The cvar to disable autoloading of Scuba Steve's conpics is autoloadconpics.
Some questionable fixes as usual.
The 32 bit version should run on XP changing the OpenAL32 and ZMusic dlls.
And more stuff i can't remember right now, try it.
Windows 64 bit
Windows 32 bit
The source is here:
https://github.com/drfrag666/gzdoom/commits/master
