Roll for your life: Making randomness transparent in Tharsis

Things are not looking good aboard the Iktomi. For the last few weeks, my crew of four (down from six after the meteor storm) had been doing an excellent job of repairing hull breaches, plugging radiation leaks and generally keeping the horrors of space firmly outside our humble vessel. Then our ship doctor was killed trying to fix our greenhouse, and our idiot mechanic failed to repair our life support center. Now the captain’s got to do it, and the odds are next to impossible.

Well, more specifically, the odds are one in 36.

Fixing our life support system will take 12 repair points, and our captain only has two six-sided dice left to roll. To repair the system, and save the lives of her crew, she has to roll two sixes. Anything less, and it’s game over.

I hit the “ROLL” button, and the dice clatter across the screen, tumbling as if over a glass tabletop. Underneath them, the captain of the Iktomi works furiously, jabbing some wires with a futuristic welding torch. I don’t realize it until later, but I’m holding my breath.

The dice settle,  and there they are: twelve beautiful pips of salvation. We just might make it to Mars after all.

But one second earlier, with all my plans unraveled, I had given myself up to fate. This moment, with the tension and stakes both at stratospheric levels, is what systems designer Zach Gage was hoping to create for the players of Tharsis. What he wanted, said Gage in a conversation with Gamasutra was “to build a game where the entropy and randomness of dice is exciting.”

Tharsis is essentially a game about crisis management. Each turn, various modules aboard the Iktomi will break; it’s up to your crew to repair them before the ship, or they themselves, suffer damage.

But even though success depends on the roll of a die, Gage argues that Tharsis isn’t substantially more random than most games: “A lot of games use random number generation, but that’s usually under the surface...when you look at roguelikes, there’s tons and tons of dice randomness. How much damage your weapon’s going to do, your chance to hit, your enemy’s chance to hit. ” The difference, according to Gage, is that the foundations of randomness on which Tharsis is based are open and viewable to the player.

If anything, the team on Tharsis had trouble creating enough randomness with dice alone. “Something I didn’t see coming, with six-sided dice, is they’re actually not very random,” says Gage. “I know that’s sort of counterintuitive to say, but because they only have six possible answers, they start to shape into curves very quickly. The optimal number of dice you need to solve an event very clearly materializes.” If the player needs to roll a seven, they can reliably commit two dice to a module without having to account for much variety.

One of the ways Gage accounted for statistical curves was introducing the hazard dice system, which makes certain numbers bad or even dangerous to roll. A stasis die will lock a low roll like a one or two in place, preventing you from rerolling, while an injury die will result in lost health for your crewmember. “If sixes are costing you health, subtracting from your other resources, it makes sixes a lot less good,” says Gage.

Despite the challenges in designing a system around them, Gage stuck with dice because of their accessibility: he wanted players, no matter their familiarity with percentage and mechanics, to understand what they were risking. “If something says you’re going to have a 90 percent chance and you fail, you think it’s unfair,” said Gage. “But if somebody says ‘You’re going to be successful at this unless you roll a one on this ten-sided die,’ and you roll a one, it’s kind of exciting.” 

The difference, according to Gage, comes down to the physicality of dice. “We understand things that we can hold in our hand. When things get abstract, especially with math, it becomes very difficult. Human beings just have this innate understanding of stuff that we can touch and hold and turn, and look at. The dice in Tharsis are an analogue for something everyone is familiar with.”

Which, of course, made getting the dice right all the more important. The dice in Tharsis don’t actually function on a random number generator; they’re objects responding to physics. “I thought that was really important,” says Gage. “Games that use dice often use dice wrong. They don’t do it with physics, and I’ve never really known why.” After actually implementing this system, Gage learned the hard way, facing technical problems regarding the weight and colliders of the dice.  

There are benefits to recreating dice within a controllable system, though. “When you roll dice in real life, you feel like they have a settling moment, where you wonder what it’s going to be,” says Gage. “In reality, it’s not there--dice settle very quickly. With digital dice, we can give you that moment.” In Tharsis, the dice are less affected by gravity, which makes them settle in a slower, floatier way than their real world counterparts. It reliably creates heart-in-your-mouth moments, like in a sports movie when the basketball is rolling around the rim for what feels like eternity as the clock runs out.

Some would call the systems in Tharsis too close to gambling, but Gage doesn’t mind the comparison. “Gambling is really fun,” says Gage. “Obviously, gambling is rife with problems, but it’s something that humans enjoy doing.” Because of the unethical connotations that come with gambling, Gage theorizes, “A lot of game designers have fled away from gambling, and tried to make games that minimized randomness, or didn’t explore it at all.” In designing the mechanics for Tharsis, Gage hopes that other developers might choose to embrace the excitement of randomness once again.