ReactOS has been in development for 28 years now and today its developers are noting on X the ability to run the Windows version of Half-Life. Some years ago were reports of the Half-Life game at least initializing under ReactOS while given today's X coverage, it seems to be the first time reported of the game successfully running on ReactOS and handling it in-game.
Granted, these days you can run Half-Life on Linux and it works well on other platforms via Wine, it's fun seeing Half-Life now running on ReactOS at it continues persevering in its quest of Windows binary compatibility.
ReactOS user "Zombiedeth" got Half-Life running on a Dell OptiPlex system with a Core i5 2400 Sandy Bridge processor and NVIDIA GeForce 8400GS graphics.
Details on X for those interested.