Half-Life 3 might not ever happen. Valve, its developer, hasn't released any newHalf-Life material in nearly 10 years, andHalf-Life 2: Episode Three has gone from delayed to vaporware to fundamental mystery of the universe. Any remaining glimmer of hope was all but extinguished last month when Marc Laidlaw, who wrote the groundbreaking series of first-person shooters, confirmed at last thathe'd left Valve after 18 years.

But there's hope, of a sort.

Last week,Prospekt launched on Steam, Valve's digital game store. The game, which features scenes and characters fromHalf-Life and bears the series' iconic logo design, bills itself as a sequel to the 1999 spinoffHalf-Life: Opposing Forces. But Valve didn't make it.Prospekt is the work of game designer Richard Seabrook, who started out crafting a series of themed levels and found himself, unexpectedly, earning Valve's approval to useHalf-Life's assets.

"I never set out to make a follow-up toOpposing Force," Seabrook says. "It evolved into that."

Seabrook simply wanted a job. "I was fresh out of university and I had no experience," he said. This was in 2012, when the British economy was rough for a recent graduate. He found he couldn't get any jobs in game development outside of basic testing and bug reporting. After a while, he'd had enough. "I decided I was just going to make a game and send it to Valve as a job application, to try to get a job as a level designer there."

So in 2015, after working on the game for a solid eighteen months, he mailed an early version ofProspekt along with his dissertation on game design to Valve's HQ in Bellevue, Washington. He didn't hear back, so in early June 2015 he dropped the game onto the Steam Greenlight service, where Steam users vote on which in-development games they'd like to see on the digital store. His designs generated so much interest that Valve finally reached out.

Before he knew it, Seabrook was making an official unofficial sequel, "a little slice ofHalf-Life."

"They said, yep, this is all yours," Seabrook says. "The only thing I couldn't use was the voice acting. But they said, yep, go for it, you can use all the IPs, you can take stuff from multiple IPs, you can do whatever you want."

So long as it was able to slot into the existingHalf-Life universe, Seabrook could do whatever he liked and sell it on Steam with Valve's blessing.

Prospekt, then, is a strange thing: an unofficial yet officially sanctioned sequel, sold for profit on the original creator's storefront. Steam's near-monopoly on PC gaming sales gives it the ability to act as its own publisher, sanctioning and legitimizing fan products at its leisure. Valve has always had a strong give and take with fans---the incredibly popular shooterCounter-Strike began as a fan-made mod, before Valve hired its creators. But this arrangement is less of a collaboration and more giving fans the keys to Gordon Freeman's house, returning to grab a cut of the profits later.

It's a canny solution for Valve, which seems to have moved away from single-player game development in favor of longterm support of multiplayer titles likeDOTA 2 and managing the behemoth enterprise that is Steam. With a minimum of work on the company's part, fans can fill in the gap of franchise maintenance, keeping interest primed if Valve ever wants to return to that well.

It's not the first time the company has done it. Last year, a beta version ofBlack Mesa, a remake of the firstHalf-Life, went up for sale on Steam. With sharper textures, some smoothed edges, and additional youthful flair,Black Mesa is a revision ofHalf-Life for modern technology and nostalgic audiences.

Prospekt doesn't quite match the brilliance of the official games. One of the most memorable aspects ofHalf-Life 2 is the sense of things increasingly spiraling out of control; it's a stressful theme park ride, escalating as you shoot and puzzle-solve your way out of disaster after disaster.

InProspekt, the player follows a similar rhythm in a less artful manner. After being summoned out of a cosmic prison by a friendly alien race, your character is sent to help. He's teleported to Nova Prospekt, a prison featured inHalf-Life 2, to support the series' crowbar-welding protagonist Gordon Freeman from behind the scenes. There, he fights the humanoid alien hordes of the Combine, first in the claustrophobic corridors of the prison and then in a variety of wide-ranging and familiar locales.

The game does little to hide the fact that it's made up of a handful of encounter types remixed in a few different ways: a shoot-out here, a jumping puzzle there, that sort of thing. Its repetitive nature, high difficulty and occasionally boring level design, began to grate on me. Other reviews are mixed, with some players criticizing it for being a thin, straightforward iteration on an old design model.

"What can I say?" Seabrook said in response. "I did my best as a team of one to get you a product from phase zero to Steam distribution. I've had some people say to me, 'Where's the new weapons?' 'Where's the new models?' I mean, you can have all of that if you want me to add two years to the development time."

Seabrook says playing with the design of the fiction ofHalf-Life was satisfaction enough. "To have got this far and have managed to distribute on Steam to thousands of people, for the first game I've ever developed, yeah, I'm really satisfied," he said.

"The fact that Valve sat around the table and said, y'know what, this guy has made a game that's decent enough for us to approve and sell on Steam, that's given me a huge amount of vindication."