Endless Runner

Setting Up an Endless Runner in Unity Without Losing Your Mind

Most tutorials on endless runner mechanics start with the basics — moving terrain, spawning obstacles, detecting collisions. The problem is they skip the part where your game chokes on actual device performance by level three. I spent about six months working through this exact issue while building a mobile game that used the endless runner framework, and here is what actually matters when you ship something playable. The core mechanic of an Endless Runner isn't really about running at all. It is about recycling geometry and managing object lifetime. You create a track section, move it behind the player camera, reset its randomization values, and push it back into a queue for reuse. The player never notices the recycling because the noise is masked by the constant forward momentum and audio. I ran into a specific issue early on where my pooling logic was causing stutter spikes on mid-range Android devices. The problem wasn't the pool size itself — it was that I was calling Instantiate and Destroy on a handful of "rare" obstacle types that lived outside the main pool. Every time a rare variant spawned, it triggered a garbage collection cycle that caused a visible frame drop. The fix was simple but easy to miss: put everything in the pool, even the rare objects. Pre-allocate twenty instances of every obstacle type at startup, disable them all, and only toggle active state during gameplay. This eliminated the GC spikes entirely and brought my frame times down from an inconsistent 18-35ms to a steady 14-16ms on the same hardware.

Object pooling is standard practice, but most people apply it only to the common assets. That is where the bug hides. The uncommon assets are the ones that surprise you during profiling. For the track itself, I use a simple chunk-based system. Each chunk contains about 30 meters of terrain with randomly placed obstacles, collectibles, and minor elevation changes. When the last chunk fully passes behind the camera, it loops back to the front. The key detail is that the chunk spawning happens slightly ahead of where the player will be — roughly one chunk distance early. This gives the CPU a predictable window to evaluate position and randomization without competing with the render thread.

Speed Scaling and Difficulty Curves

Beginners usually approach speed scaling by simply multiplying the move speed by a constant over time. This produces a linear difficulty curve, which feels flat after about forty seconds. The better approach uses a logarithmic scale. Speed increases by smaller increments as time progresses, which keeps the game feeling challenging without suddenly becoming unplayable. Here is the formula I settled on after testing several variations: currentSpeed = baseSpeed + (log(timeElapsed + 1) * scalingFactor)

With a baseSpeed of 12 and a scalingFactor of 1.8, you get a smooth acceleration that reaches about 18 units per second at sixty seconds. The player perceives the game getting harder because obstacle density increases alongside speed, not just raw velocity. Obstacle density should also scale independently from speed. A common mistake is keeping the same obstacle frequency at high speeds, which makes the game unfair rather than difficult. The gap between obstacles needs to scale proportionally with speed so reaction time stays roughly consistent. I calculate gap distance by dividing currentSpeed by a target frequency value, which naturally widens gaps as the game speeds up.

Collision Detection That Doesn't Break on Mobile

Using BoxColliders for every object in your scene works fine on a desktop, but mobile devices have fewer cores and slower physics budgets. My original build used a single compound collider per chunk for the floor, which was fast but made individual obstacle detection messy. I switched to a hybrid approach: one large trigger collider on the chunk for ground contact, and individual BoxColliders only on obstacles that the player can actually hit. Collectibles use sphere triggers set to isTrigger mode so they don't interfere with the physics solver. This reduced my physics update time from roughly 4ms to about 1.2ms on a Galaxy S10, which is significant when you are already pushing close to the 16ms frame budget for a 60fps target. Another thing nobody mentions: if your player character has a Rigidbody, make sure it is set to Kinematic. A non-kinematic Rigidbody in an endless runner fights against your manual movement code and creates unpredictable jitter. Set it to kinematic, move the transform directly, and handle all collision response through trigger events instead of physical forces. This gives you deterministic movement which is essential for fair gameplay.

Common Pitfalls When Building an Endless Runner

The biggest pitfall I see is not planning for session length. An endless runner without a defined target play session feels arbitrary. Players quit when there is no sense of progression or goal. Even if your game has no levels, you should define a score threshold, a distance milestone, or a collectible target that gives players something to work toward before they naturally stop. A secondary issue is audio design. The constant background loop of an endless runner becomes fatiguing quickly if it lacks variation. I solved this by layering three audio tracks that fade in and out based on speed thresholds. Track one plays at base speed, track two crossfades in above 15 units per second, and track three sits on top at maximum speed. Each layer has different instrumentation so the shift is noticeable but not jarring. Also consider implementing a checkpoint system for longer sessions. Without it, players lose everything on death and the frustration builds fast. A simple distance-based checkpoint that saves the furthest point reached reduces retry friction significantly. I found that adding checkpoints after every 100 meters of travel increased my average session length from about 45 seconds to nearly 3 minutes without changing any other mechanic.

There is no perfect implementation of an endless runner. The genre inherently trades depth for accessibility, and no amount of polishing changes that. If your goal is a casual mobile title, object pooling with hybrid colliders and logarithmic speed scaling will get you a stable build. If you are targeting competitive or speedrun audiences, you will need to add frame-perfect input handling and deterministic random seed generation, which is a much larger undertaking. Choose your audience early and design around their expectations rather than trying to serve both.