How to Soak-Test Your Game for Long-Session Bugs

Some of the most frustrating bugs—memory leaks, accumulating state, slow degradation, resource exhaustion—only manifest after extended play, which means short testing sessions never catch them, and players discover them after an hour of enjoying your game. Soak testing, running the game for long durations to surface these time-dependent bugs, is how you catch the problems that only emerge over time, before players do.

Some bugs only appear over time

A whole category of bugs is invisible to normal testing because it only manifests after extended play. Memory leaks accumulate slowly, becoming a problem only after the game has run long enough for the leaked memory to add up to a crash or severe slowdown. State that accumulates without being cleaned up—objects that pile up, lists that grow unbounded, resources that aren't released—degrades performance or causes problems only after enough has accumulated, which takes time. Slow degradations of various kinds, where something gets gradually worse, are fine in a short session and broken in a long one. These time-dependent bugs share the property that short testing sessions, where you play for a few minutes and move on, never run long enough to surface them, so they pass all your normal testing and then strike players who play for an hour or more, which is exactly your most engaged players in your most important sessions. The bug that crashes the game after ninety minutes of play is invisible to a developer who tests in ten-minute bursts, but devastating to a player deeply immersed in a long session, and these long-session bugs are some of the worst because they hit engaged players at bad moments and are hard to diagnose because they depend on accumulation over time.

Soak testing—deliberately running the game for extended durations—is how you catch these bugs before players do. The solution to time-dependent bugs is to test for time: deliberately running the game for hours, or leaving it in extended play, to give the time-dependent bugs the duration they need to manifest. This soak testing surfaces the memory leaks, accumulating state, and slow degradations that short testing misses, by actually running long enough for the accumulation to reach the threshold where it becomes a visible problem. Soak testing can take various forms—playing for a long session, leaving the game running in a state that exercises the systems prone to accumulation, or automating extended runs—but the essence is duration: running long enough that time-dependent problems have time to emerge. Watching for the signs during a soak test—memory climbing and not coming back down, performance degrading over time, resources accumulating—reveals the bugs and often points at their cause. This connects to the value of monitoring memory over time to find leaks, since memory leaks are a prime example of a bug soak testing catches. Because long-session bugs are both serious (hitting engaged players at bad moments) and invisible to normal testing (which is too short to surface them), soak testing fills a crucial gap, catching a category of bugs that would otherwise reach players undetected. The investment is straightforward—deliberately test for extended durations, watch for the signs of accumulation and degradation—and it catches the frustrating, hard-to-diagnose, engaged-player-affecting bugs that only time reveals. Adding soak testing to your process, so that you run the game long enough to surface time-dependent problems, is how you catch the long-session bugs that short testing structurally cannot, protecting your most engaged players in their most important sessions from the memory leaks, accumulating state, and slow degradations that would otherwise strike them after an hour of play.

Let real players be the judge

It's remarkable how differently real players behave from how you imagine they will. The tutorial you think is obvious confuses them; the feature you agonised over goes unnoticed; the thing you almost cut becomes their favourite. None of that is visible from inside your own head, which is why watching real people play is the single highest-leverage thing most developers under-do.

Watch without intervening, resist the urge to explain, and pay attention to what players do as much as what they say. Their confusion and their choices are data, and acting on that data is what turns a game that works for you into one that works for everyone.

Polish where players actually look

Polish is not evenly valuable. Players form an impression in the first minutes and spend most of their time in the core loop, so effort spent there returns far more than effort spread thin across content few people reach. The opening, the moment-to-moment feel, and the things every player touches are where polish converts directly into how good the game feels.

Be deliberate about it. Make the first impression strong and the core interactions satisfying before widening out, because a great core with less content almost always beats a sprawling game that never feels good to play.

Scope is a decision, not an accident

Almost every overscoped game got that way one reasonable addition at a time, with no single decision ever feeling like the mistake. The finish line recedes a little with each new feature, and because the project always feels nearly done, the developer rarely notices how far the goal has drifted until they're exhausted and the game still isn't out.

Treat scope as something you actively decide rather than something that happens to you. Write down what the finished game contains, make every addition a conscious trade against that, and keep most new ideas in a backlog where they belong — because a small game you finish beats a large one you abandon.

Measure before you optimise

Intuition about what's slow, what's confusing, or what's driving players away is usually wrong, and acting on it wastes effort on problems that don't matter while the real ones persist. The developers who improve their games efficiently are the ones who measure first — profiling performance, watching real sessions, capturing actual errors — and let the data set their priorities.

It's slower than trusting your gut, but it's the only approach that reliably improves the game instead of just changing it. Find the biggest real problem, fix that, and measure again, rather than optimising guesses.

The first impression is most of the battle

More players leave in the opening minutes than at any other point, which makes the first few minutes the highest-leverage stretch of the whole game — and also the part the developer can least see clearly, having played it a thousand times. What feels obvious to you is often confusing to someone seeing it fresh, and that gap quietly costs you players before they ever reach the good part.

Get the player into the interesting part fast, let them feel competent quickly, and watch first-time players go through the opening without helping them. Nobody quits a game they're enjoying, so making the early minutes land is most of the battle for retention.

Long-session bugs—memory leaks, accumulating state, slow degradation—only appear over time, so short testing misses them. Soak-test by running the game for hours to catch them before players do.