At a glance
Day of Defeat has a Mac version: Steam sells it for macOS. The Mac requirements list only Intel: on Apple Silicon Rosetta 2 runs it, and old Mac versions sometimes do not start on current macOS. Try it in Steam for Mac first.
Day of Defeat came out on Steam on 1 May 2003, made by Valve.
What your Mac needs
The Mac requirements list only Intel.
Minimum macOS in the Steam requirements: 10.6.3.
Steam requirements list at least 1 GB of memory for Day of Defeat.
Allow about 4 GB of disk space for the Mac version.
How to play
Open Steam for Mac and install Day of Defeat as usual.
If the Mac version will not start, you can install the Windows version through Uncork: download Uncork, sign in to Steam and install Day of Defeat from there. We have not tested it ourselves.
The Windows version through Uncork needs a Mac with Apple Silicon (M1 or newer).