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The Game That Writes Itself

Mercury is a new kind of sandbox game that's completely controlled by the players. As you might expect, things are getting weird.

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This is Mercury, a Rogue-like game developed by 22-year-old designer James Lantz. The letter "A" is you, an anonymous adventurer exploring level after level of an infinite dungeon, killing every monster you find. It's a formula game designers have been tinkering with for 30 years, with one important twist: this time, the players are supplying all the monsters.

The game started with just one character class and one kind of monster, but every few days since then, whoever has the top score gets to add a new character type, monster, or item to the mix. It started out simple — a stronger hero with less armor, a few more dangerous monsters that seasoned players would know to avoid. But with each new piece of user content, Mercury got weirder. As of press time, the game has been through nearly 50 cycles, with 20 kinds of monster and nearly 15 character classes.

The result is a new kind of sandbox game, one where the players are in charge of how the game develops, and the developers are left to sit back and watch. "I just had no control over anything that was coming into the game," Lantz told me. "Half the people I talked to said, 'you're going to have a bunch of dick monsters.'"

The good news is, that hasn't happened yet.


Lantz describes the game as an experiment in balancing, determining exactly how powerful a game's enemies should be to make it challenging but not impossible. It's not uncommon for a company like Blizzard to bring in a few of their most obsessive fans to find the perfect balance in beta-testing. Mercury just automates the same process, creating an ecosystem where the game balance is entirely determined by users.

At first, that meant choosing between more powerful heroes and more powerful monsters, but soon it developed into a strange kind of cat-and-mouse, with players building bizarre character classes to fight a specific type of monster type, and vice versa. Users can choose to eliminate a class or monster instead of adding one, but, "people are really hesitant to do it," Lantz said. "People feel bad killing something someone else made."

You can see one example in the GIF above. The white skull is a Ghost, which freezes the player but does no damage. Players responded by creating classes like the Bramblebrush, which deals splashback damage every time it's attacked. Once players cracked that version of the game, they'd add something else that neutralized the Bramblebrush, iterating into a blindingly complex network of weapons and skills. Instead of balancing the game, they've transformed it.

If Mercury has dodged the usual trolls, the community has created issues of its own. The web of obscure classes can be difficult for newcomers to navigate, which has made it easy for the same small cadre of early adopters to keep hold of the high score. As a result, Mercury has had a hard time holding on to new users. Lantz has has seen over a thousand people playing the game after a good writeup, and then seen the number drop back down to 50 within a few days. He might want lots of users, but the early adopters are happy to keep the game for themselves, and they may have more power over Mercury than anyone else.

Lantz has plans to spin the game off into different standalone installations, so new players can start the game-building process from the beginning. That would move Mercury out of MMORPG territory and put it closer to obsessive board games like Settlers of Catan, the kind of thing a small group of friends might play together without the thrill of competing with the hordes of the internet.

As Lantz put it, "I'm hoping I can set it free."

Contact Russell Brandom at

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