The current alpha 23b has some problems with the new Ryzen CPUs.
First problem ist the correct hardware detection. This leads to an crash by starting the game.
Second problem are random slowdowns and speedups while playing the game.
Both problems will be addressed with the next alpha 24. Until than the game has to be individually patched. Follow the instructions below.
Windows:
Replace the files of
%localappdata%\0 A.D. alpha\binaries\system
by the files