UPDATE 9/4/15 11.45am: Halo Online gameplay footage has surfaced, showing a development build of the game where modders have now managed to get the shooter's online multiplayer working.
The team-based mode allows you to drive the Warthog and other vehicles. On-foot combat is also possible.
Halo Online is planned for release in Russia only at some point later this year. It's yet to launch even in alpha.
Watch the gameplay below, until Microsoft likely pulls it offline.
ORIGINAL STORY 7/4/15 10.20am: Modders are already hard at work picking through Halo Online, Microsoft's upcoming Russia-only PC shooter, with an eye to removing its free-to-play microtransactions.
The game is being developed by 343 Industries, Master Chief Collection co-developer Saber Interactive and Russian publisher Innova Systems, but has yet to even launch its closed beta.
Regardless, an internal build of the game has found its way online and Halo fans are now investigating Halo Online's two major points of fan contention.
Firstly, that Microsoft currently only plans to launch the game in Russia.
Secondly, the fear that the game will be crippled by pay-to-win microtransactions.
Halo Online's first trailer, included below, reveals how players will be able to use credits to purchase customisation options for their character. No other payment details have been released, but modders are pessimistic:
"We of course still don't know 100 per cent what items are purchasable with real money, but it would appear at first glance to have pay-to-win potential," modder Woovie told TorrentFreak. "We also of course want to play this game, which as far as we see, is a Russian market only game.
"Microsoft is probably quite bothered by what we've done already as these files were leaked. We obtained the files from a user on 4chan's /v/ board. From there, user Emoose proceeded to create a hack that would allow the client to load files and thus get in game. The files we have are definitely an early internal alpha. A lot of left over code from other Halo games."
The hack, named ElDorito, is a launcher that will run the leaked code without any issue. But its success quickly drew Microsoft's attention.
Microsoft issued Digital Millenium Copyright Act (DMCA) takedown notices to the copy of ElDorito posted on collaborative code-sharing site Github, and it has since disappeared. But the ElDorito team hasn't been put off.
"In terms of DMCA/C&D mitigation, we have made redundant git backups on private and public git servers," Woovie continued. "This is to ensure we will always have one working copy. These are being synchronised so that data is always the same.
"Further DMCAs may happen potentially, it's not really known at the moment. Our backups will always exist though and we will continue until we're happy."
Team ElDorito continue to probe the game's free-to-play potential - with an eye to releasing a version without microtransactions should Microsoft's own version of Halo Online prove to enable pay-to-win.
"The game was going to be free in the first place," Woovie reasoned. "The PC audience has been screaming for Halo 3 for years and years, and we saw the chance with this leak. The fact that we could, in theory, bring the game that everyone wants, without the added on stuff that would ruin the game, that's something we'd be proud of."
In a new statement to Eurogamer, Microsoft reiterated that that the game would remain a Russia-only experience for the time being:
While we're thrilled there's so much interest outside of Russia, the beta of Halo Online is a PC experience tailored specifically for the tastes, tech and infrastructure of the Russian market and furthermore, is still in an early state," a company spokesperson explained.
"As such, we want to ensure a quality experience for our beta participants within Russia which could be impacted through unauthorised use."