An endless runner has no finish line. Your character moves forward automatically, the world keeps coming and the only question is how long you last. The format is simple enough for one button and deep enough to keep players at it for years. Run 3 and Slope, both once listed on this site, are among the best-loved browser examples.
A short history of the endless runner
Canabalt, a 2009 browser game by Adam Saltsman, is usually credited with setting the template: a man running across rooftops, one button to jump, speed always rising. Mobile phones made the format huge. Imangi Studios' Temple Run (2011) moved it into 3D behind the character, and Subway Surfers (2012) turned it into one of the most-downloaded mobile games ever made. In the browser, the genre kept its experimental streak.
The browser runners worth knowing
| Game | What makes it different |
|---|---|
| Run 3 | Joseph Cloutier's 2014 game: run through tunnels in space and rotate the whole tunnel when you hit a wall. Started in Flash; now widely played in HTML5 versions |
| Slope | Steer a ball down a neon slope of ramps and gaps at rising speed; brutally simple and very fast |
| Tomb Runner | A Temple Run-style chase through ruins |
| Grandpa Run 3D | A comic 3D runner in the same mould |
| Canabalt | The 2009 original, still a model of clarity |
Run 3 deserves a special mention. Its gravity-shifting tunnels, unlockable characters and long story mode made it one of the most searched browser games of the 2010s, and it outlived Flash by being moved to newer web technology. More on that change in the death of Flash.
How the levels never end: procedural generation
Endless runners usually build their world from pieces. A designer makes dozens of short segments, such as a gap, a low barrier or a narrow bridge, and the game strings them together as you play, choosing each next piece with a pseudo-random number generator. Rules keep it fair: no impossible jumps, harder pieces only after a certain distance, rest sections between hard ones. Some games use a fixed "seed" so everyone gets the same sequence in a daily challenge; others change it every run.
Seeds, streaks and the slot machine in your pocket
That random number generator is the same kind of machine that sits inside a modern slot. A pseudo-random generator takes a seed and produces a long, unpredictable-looking stream of numbers; the runner uses them to pick the next obstacle, the slot uses them to pick the reel positions the instant you press spin. Nevada and other regulators require gaming machine generators to be tested so that results cannot be predicted or influenced, and our article on the RNG behind slot machines explains how that works.
The psychology is related as well. Runners are built around the "one more go" feeling: a run ends, a best score flashes, coins you collected count up, and the restart button is under your thumb. Mobile runners add daily missions, mystery boxes and streak rewards that pay on an unpredictable schedule. Those are exactly the techniques we describe in variable rewards in casinos and mobile games. Knowing the trick does not spoil the game, but it helps you decide when to put it down.
Tips for runners
- Look further ahead. At high speed, react to the obstacle after next, not the one in front of you.
- Find your rhythm. Generated levels repeat patterns; learn the common pieces and your hands will follow.
- In Run 3, use the walls. Turning onto a wall is often safer than jumping a gap.
- Play short sessions. Scores tend to drop as you tire. Stop on a good run.
