In an update posted (opens in new tab) to their Steam page, the team behind the mod Lambda Wars have announced that the Half-Life 2 real time strategy project has left beta. The launch includes singleplayer, co-op, and multiplayer modes. Lambda Wars has two factions, the Combine and Rebels, and lets players refight the battles of Half-Life 2 from a top-down angle. The launch update implements the "lost" enemies of Half-Life 2, like the crab synth and mortar synth, found in artbooks of the original game.
The mod itself is actually based off the code of Alien Swarm, the Source engine based mod-turned-full-game released for free by Valve in 2010. In a post on Reddit, one of the mod team outlined how many people have worked on the game over the 13 years of development: "Many developers have come and gone, but the lead programmer started and finished the project." The developers have received a handful of monetary donations for their time, but ultimately the game was a passion project.
For my part, I can remember seeing the first steps at this mod over a decade ago, when it was called Half-Life 2: Wars and wanting to play it very badly. That's now, incredibly, something I can do. I love these inspirational mod stories for just that reason. They're a testament to what people can achieve in life outside their "real jobs." You can find Lambda Wars on Steam.