Liang Qi, biologist, mineralogist, expert cave diver and celebrated spokesperson of the Global Space Initiative, twisted his torso and wriggled downward through the tiny opening. Grabbing the rope, he slid the final metres to the floor below, the impact producing hazy spheres of microscopic particulate matter. His headlamp scanned the tunnel ahead. Yet another lava tube, immense, the curved walls meeting overhead and submerging into blackness. He contemplated the timeless span these caves had lain, anonymous and still, since that moment billions of years ago when lava from the Tharsis Uplift had flowed over the surface, leaving them in its wake. The tunnel was stark and cold, but not as hostile as the surface, where the atmospheric pressure and temperature never rose above the triple point of water. Here, at least, liquid water could be found. He had seen it laying in deep pockets and had seen a thin layer of pallid scum, actual extraterrestrial life, around its perimeter. He dared not touch it or even get close without the sampling equipment, and that had been lost in the cave-in. This lava tube, like a dozen before it, was his last hope for reaching safety.
So he walked, and shadows slid behind columns reminiscent of melted wax, and his mind instantly rejected a thing it had seen: a flash of colour in the slotted light, a shape expanding. He froze. His scientific training protested as he crept forward, but the complaint was lost in the din of his human curiosity, so powerfully provoked. He rounded the corner and there was the thing, tangible and real, growing, it seemed, out of the ground. A plant? An animal? Better not to rely on Earth paradigms of life: that’s what this was, a true alien lifeform. It stirred and uncurled, seeming to stretch, no… it was growing. It was reaching toward him, or rather, he confirmed with some experimentation, his headlamp. Why would a lifeform that had evolved deep underground on a dim planet be so responsive to light?
That’s what I had in mind, anyway, when Tiger Style first decided to make a sci-fi game about discovering life in a cave on Mars. I was drawn to the science of real-life space exploration, imagining moments that could happen decades in our future. What might they be like? Rather than alien fangs and laser pistols, I was moved by the serious and credible. But does pond scum make for good gaming? Our first prototype suggested not, it wasn’t working. Too slow, too cerebral.
That may seem obvious, but I believe a game with this deliberate pacing could succeed. It might require more patience and imagination, but those are qualities I respect. Maybe someday, but today it’s not the cultural precedent, and our prototype wasn’t proving the potential. An expansive console production with detailed 3D environments and amazing lighting technology maybe could. It’s harder to feel immersed on an iPhone screen.
More importantly, that’s a hard story to work with, because much of it is internal to the character, realisations and contemplation, perfect for literature but not games. The contrast between the innocuousness of the pond scum and its potential fearsome killing ability is interesting because we can see into the character’s mind, but how might you adapt that? Our prototype had a cool headlamp lighting model, platformer movement and exploration, but by contemporary standards there wasn’t much to find. You might discover an interesting alien plant, but the ten seconds it took to grow seemed unrealistically fast on one hand and tediously slow on the other.
What I’ve learned in this process is that an important measurement of how engaging a game will be is something I call its interaction density. Sid Meier describes games as a series of interesting choices, and you can expand out of his turn-based worldview to include the rapid impulses and responses of action games. Interaction density is how frequently these happen, especially ones that really matter. You might travel down a lava tube for two minutes, but if you only touched the screen once, that’s low density. Farther in, the player might decide to grow a plant by scaling a cliff, gathering water, climbing down, shining the lamp on the plant, throwing the water, missing, and starting again. This requires time and attention, but there are few points where it might become varied or dynamic. One decision, minutes of rote execution. Low interaction density.
I think most designers have instincts for this, and the obvious answer is to crank the knob. Because my predilection is for inventing new types of gameplay, I’m wary that this approach might be dogmatic. So interaction density still isn’t the design lens I put first, but I now respect it as an important one for consideration. I only really formalised the concept as our game improved: plants grew quickly, they didn’t require your light, they spat seeds into the world automatically. It was essentially the same interactions, just made iconic rather than realistic, happening at a pace much closer to how quickly you could choose them. The loss of strict scientific credibility required a shift in tone to a more abstract and game-y game, but much of the vision is still conveyed, and our respect for the material still evident.