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Games use two types of randomness. Which one is more fair?

Or: Why that 90% to hit chance in XCOM failed

There’s one genre that this excellent video from Game Maker’s Toolkit does not address, and that’s sports, but in MLB The Show and NBA 2K particularly, I can speak to the total getting-screwed mindset of feeling like I’m getting beaten by a random number generator. That’s called output randomness, and Mark Brown does a wonderful job explaining it, and its sibling input randomness, in this video.

More importantly to us, he explains how they affect our (players’) feelings of fairness. Output randomness is best described as having an 87% chance to hit in XCOM and somehow whiffing the shot completely. (It also describes loot boxes, which no one likes.) But XCOM is still an excellent, well-loved series. Why?

That’s partly because the blind chance, however brutal and unfair it may seem, really challenges the player’s capacity for tactical thinking — the point of XCOM. Brown observes that the best XCOM players are the ones who have strong backup plans, for when that can’t-miss flanking shot actually does. Furthermore, a bad outcome from output randomness can, in effect, become useful input randomness for the player’s next turn.

Input randomness is essentially information before the action: the draw of cards before a turn, or the creation of a procedurally generated map. That gives the player something to strategize against, and for sure it feels like a fairer way to handle an element as necessary to games as randomness.

Subset Games delivered FTL: Faster Than Light in 2012, and it’s a game packed with output randomness. Still, it was popular and enjoyable. But when Subset came back for its second act six years later, 2018’s equally enjoyable Into the Breach, it was all input randomness — indeed, players know most everything about what the enemy is up to before making their decision. That was a deliberate design choice, said Subset’s Justin Ma.

Well, except for this: There’s one element of output randomness in Into the Breach, and that is in the player’s built-in defense system, which can roll the dice and save their skin, completely at random. And that’s because, as Ma observed, no one ever complains about output randomness that breaks in their favor. And when my 25-foot heat check jumper in NBA 2K20 actually goes in, I’m not exactly calling bullshit on the CPU.

In all, Game Maker’s Toolkit delivers another thoroughly enlightening and educating look at something that usually seems so opaque and/or unfair to players — indeed, developers sometimes goose their background calculations just to comport with players’ mistaken ideas of how odds actually work. Next time you think your game’s screwing you over, refer back to this video.

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