Nuclear Throne: a case study in player feedback

Nuclear Throne, an early access retro-styled action game from Vlambeer, has held my attention since I bought it last week. The randomly generated levels maintain balance, the game is challenging but rarely unfair, and the game looks great, but what is most impressive is the ‘juiciness’ it provides.

Juiciness, in games, is usually described as ‘the satisfying feeling when potential energy is converted into kinetic energy.’ More loosely it’s the feedback presented to the user upon input, and it can have a huge impact on the ‘feel’ of a game, the part that talks to a player’s subconscious. Nuclear Throne is at its juiciest, appropriately enough given its action focus, the moment you fire your weapon.

Picking up a weapon

We’ve heard that half the fun is in the anticipation, and Nuclear Throne provides this by hinting at the kinetic energy present the moment you pick up a weapon. A crossbow will show a red line stretching across the screen from the character, and the player’s view will shift slightly further away from the character and towards the crosshair, hinting at a long range accurate attack. Change weapons to a shotgun and the screen will close in on the player again, as if zooming in on the focus point of action.

Firing

Audio and visuals combine to make every click feel powerful and physical by maximizing feedback. The screen judders back for a fraction of a second away from the direction of firing, imitating the kick of every trigger pull. Larger weapons have a more pronounced screen shake, that appear to shake the room instead of just tapping it back and almost appear to push the character backwards. Simultaneously, you’ll hear the sound of the gun firing, and each weapon type is immediately recognizable, with shotguns giving a low bark and lasers a brief zap.

Impact

Unlike the firing noises, the impact sound effect is nearly always the same. When the bullets are flying and you’re racing for cover while firing blindly into a mass of enemies, the brief thud of impact indicating one of your shots connected provides immediate feedback to the player. In addition, to emphasise the amount of potential energy expended with each shot, upon death the cartoonish enemies’ corpses will fling across the room, impacting (and damaging) environmental objects and even other enemies.

Certain weapons, like explosives, will show their impact not just with impact sprites, sound, and screen shake but by actually destroying portions of the wall around them. This destruction of what in other games would be immutable emphasises the danger to the player of standing too close, and also indicates the approximate radius of such danger.

Other weapons have their own special behaviour upon impact. Shotgun pellets reflect individually off walls, each with their own impact sound. Arrows fired from crossbows thump as they pass through multiple enemies and finally impact in a wall.

Extrinsic reward

Enemies drop experience points, and with upgrades can also provide health and ammunition. It’s also necessary to defeat everyone to proceed to the next level. These extrinsic rewards provide the end of this feedback loop, and provide a gameplay-affecting reason to re-enter the loop. The dropped vials of experience also pull towards the character as they near, like the game-world manifestation of the players desire.

Maximizing output for input

The final effect is that each weapon feels very different from any other, and without needing to spend extensive time learning each one, players can follow hints of screen shake, sound effects, projectile speed and so forth to hint at the potential uses of each. For me, this stacking of feedback all adds up to a experience that feels solid, in a way that’s easy to understand upon playing but hard to communicate otherwise.

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