How to Implement Entity Interpolation for Smooth Multiplayer

Entity interpolation is the technique that makes other players and networked objects move smoothly in multiplayer, despite their positions arriving only periodically over the network. Understanding how rendering slightly in the past and interpolating between updates produces smooth motion is essential to networked games that don't look jittery.

Interpolate between updates instead of snapping

Networked games receive other players' positions only periodically (at the network update rate), not every frame, so if you snapped each player to their latest received position, they'd jump jerkily between updates—jittery, ugly motion. Entity interpolation solves this by interpolating: instead of snapping to the latest position, the client smoothly interpolates the entity between the network states it has received, producing smooth motion between updates. To do this, the client renders the entity slightly in the past—buffering a short history of received states and rendering the entity at a time slightly behind the latest, interpolating between the two surrounding states—so it always has a 'from' and 'to' state to interpolate between, producing smooth movement. This rendering-in-the-past plus interpolation is what turns the periodic, discrete network updates into smooth continuous motion, which is why other players move smoothly despite their positions arriving only periodically. Interpolating between received states, rendering slightly in the past, is the core of entity interpolation.

The small delay is the cost, and it's worth it for smoothness. The tradeoff of entity interpolation is that rendering slightly in the past introduces a small delay—you see other players a fraction of a second behind their actual current position—because you're rendering an interpolated past state rather than the latest. This delay is small (a fraction of a second, tuned to the network update rate) and is the cost of the smoothness interpolation provides. For most games, this small delay is well worth the smooth motion, because jittery, snapping movement is far worse than a tiny delay, and the delay is small enough not to significantly affect gameplay for the rendering of other players (your own player uses prediction, not interpolation, so your control isn't delayed). The interpolation delay matters for things like lag compensation (which must account for it when rewinding to check hits), but for the visual smoothness of other players, the small delay is a worthwhile trade. Entity interpolation, then—rendering other players slightly in the past and interpolating between received states—is what makes networked entities move smoothly despite periodic updates, at the cost of a small, usually-acceptable delay. Combined with client-side prediction (for your own responsive control) and lag compensation (for fair hit detection), entity interpolation (for smooth rendering of others) is one of the core techniques of good netcode, making networked games look smooth and feel responsive. Implementing it—buffering states, rendering slightly in the past, interpolating between the surrounding states—is what turns jittery network updates into the smooth motion that makes multiplayer look good.

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.

Small and finished beats big and abandoned

A folder of impressive unfinished projects teaches far less than a single small finished one, because finishing is where the hardest and most valuable lessons live — the unglamorous final stretch of bug-fixing, polishing, and shipping that ambitious abandoned projects never reach. Each completed game, however modest, builds the finishing muscle and the confidence that make the next one achievable.

So resist the pull of the dream project until you've shipped a few small ones. Scope to what you can actually complete, finish it, and let the experience of shipping make your bigger ambitions realistic.

Entity interpolation smooths other players' movement by rendering them slightly in the past and interpolating between received network states, instead of snapping to each update. The small delay is the cost, well worth the smoothness it provides.