Spacewar is a game that draws thousands of players every day. If you search for it on the Steam store, though, you'll never find it.
You might recognise the name. Spacewar is, after all, Valve's take on an influential early video game that went by the same name. It's an extremely basic space shooter where ships are represented by little triangles, swirling forever around a doomed sun that looks kinda like a Tinker Toy. Valve made their own version as a tool for developers to test Steamworks features like achievements and the Steam Workshop.
Technically, anybody can obtain Spacewar, albeit not through regular Steam channels. Instead, you've gotta enter "steam://run/480" in Windows' "run" dialogue box, which you can access by pressing Windows key + R. At that point, you should get a prompt from Steam asking if you want to install Spacewar. That's pretty much it!
Now, here's where it gets weird: if you try to join a match or lobby, you'll find only a handful of options, at best. However, trackers on reliable sites like Githyp, Steam Charts, and SteamDB -- which all pull from Valve's own data -- say that Spacewar peaks at around 8,000 concurrent players per day. That lodges it firmly in the center of Steam's top 100. Where, then, are all these players when you try to, you know, find people to play with?
While it's not possible to ascertain the exact numbers on this, some of those people are presumably developers. Others -- perhaps even a significant portion of them -- are pirates. The basics, as relayed by Githyp, are as follows: Steam can detect pirated games, so pirates mask them with a workaround that involves Spacewar. If you see somebody in your friends list playing Spacewar, they might actually be playing a crack of a popular game.
After reading this, I did some research of my own in parts of the internet I'm not going to mention, and sure enough, this method seems fairly common, especially as a means of accessing multiplayer features even with pirated copies of certain games. I've found years-old games that employ this method, so it's by no means new. On less illicit parts of the internet, I also found people quaking in fear of getting banned for playing games this way, which was, to be frank, pretty funny. I reached out to Valve for comment on all of this, but as of writing, they still hadn't gotten back to me.
This should go without saying, but pirating shit on Steam is a bad idea. Valve can ban your account, if they deem your Deep Web crimes heinous enough. Still, Spacewar is an interesting relic from Steam's notoriously janky history, one that remains surprisingly relevant to A Certain Subset Of People.
As Steam evolves into an algorithmically driven mega-platform and Valve tries to squelch less-than-legal activities (or at least, ones that mess up their algorithm and/or bottom line), I wonder what'll become of it.