Engine Heart is a pen-and-paper RPG set in a world where small household robots are the sole remaining heirs to the planet. In some role-playing games you might take on the role of a wizard or an elf battling the forces of evil. In this game, you play a Sex Bot or an empty vending machine searching for soda cans to sell to the human corpses around you.
Engine Heart provides examples of:
- After the End: The game is set after the human race has disappered. Exactly how all the humans disappeared is never explained, and is presumably left up to the Programmer to decide.
- And I Must Scream: In the adventure "Power and Light," Frank, who has a nuclear battery, is hacked by his friends into an immobile and mute, yet still self-aware, charging station. If a PC has a nuclear or solar battery, they'll try to do the same to them.
- Artificial Intelligence: The game makes a distinction between robots, which are mobile, and A.I.s which are more intelligent and housed in buildings. Unfortunately, the A.I.s that remain alive tend to become dictators.
- Cute Machines: Every player character in the game.
- Giant Equals Invincible: Size is directly proportional to durability, meaning that larger robots are more durable at the expense of evasion.
- Humanity's Wake: The overriding theme of the game is how humanity's sapient robots adapt to their masters being gone. Many robots, particularly those with the resources to continue operating unimpeded, continue as if the world hadn't changed at all. Others are forced to prioritize the struggle for survival, are shanghaied into some other robot's mad agenda, or are left to devise new purposes for themselves in a world that's nothing like the one they were created for.
- In the Future, We Still Have Roombas: Given that all the players are assumed to be playing robots designed for specific purposes like washing cars or cutting lumber, a Roomba is a perfectly acceptable character concept.
- Power Source: In keeping with the Bradbury-themed tone of the book, robots have the option of being nuclear-powered. This removes the worry of having to ever recharge, but if a nuclear battery is overtaxed it runs the risk of exploding and destroying almost everything in the area. Even if the explosion is somehow avoided, it still takes at least an hour at absolute minimum to cool down and stabilise.
- Ridiculously Human Robot: Robots with the "Android" ability are "designed to be indistinguishable from a human".
- Robo Speak: Some robots can communicate with wi-fi, but all robots can talk to each other with a speaker and a microphone.
- Scavenger World: One of the game's main themes is the breakdown of human infrastructure. Finding a working charging station to plug in and recharge your battery can be an adventure in itself. Of course, since this is about robots, your character is as likely to be the scavenged as the scavenger.
- Shout-Out: The opening vignette features the same Sara Teasdale poem as Ray Bradbury's "There Will Come Soft Rains".
- Sliding Scaleof Robot Intelligence: Not all robots in this game are equally smart, and there are four different kinds of intelligence. Some robots are even programmed to subvert the usual scale, being able to easily interact with humans without falling into the Uncanny Valley, but not actually being very smart otherwise.
- TV Head Robot: Robots with the "Display Screen" ability "can display status messages or play video recordings" through their screens.