How to Implement a Command Pattern for Undo and Replay

The command pattern—representing actions as objects that can be executed, undone, and recorded—is a clean way to implement undo/redo and action replay, encapsulating each action as a reversible, recordable object. Understanding the command pattern is key to cleanly implementing undo and replay features.

Commands encapsulate actions as executable, reversible objects

The command pattern represents each action as a command object that knows how to execute itself and how to undo itself—encapsulating the action (and its reversal) as an object. Instead of performing actions directly, you create command objects that perform the action when executed and reverse it when undone, so each action is a self-contained object that can execute and undo itself. This encapsulation—each action as an executable, reversible command object—is the core of the command pattern, turning actions into objects that can be executed, undone, and managed. Commands encapsulating actions as executable, reversible objects is the foundation, because representing actions as command objects (that can execute and undo themselves) is what enables the undo and replay features the pattern provides.

Recording commands enables undo/redo and replay. The power of the command pattern comes from recording the command objects, which enables undo/redo and replay. For undo/redo, you keep a history of executed commands, and undoing means calling undo on the last command (reversing the action), redoing means re-executing it—so the command history provides clean undo/redo, with each command knowing how to undo and redo itself. For replay, recording the sequence of commands lets you replay the actions by re-executing the recorded commands in order, reproducing the sequence of actions—so recorded commands enable action replay. The command pattern thus cleanly enables both undo/redo (via the command history and each command's undo) and replay (via recording and re-executing commands), because the commands encapsulate the actions as recordable, executable, reversible objects. Recording commands to enable undo/redo and replay is what makes the command pattern valuable, providing clean undo/redo and replay through the recorded, reversible command objects. Combining commands encapsulating actions as executable, reversible objects (the pattern's core) with recording commands to enable undo/redo and replay (the pattern's payoff) is what makes the command pattern a clean way to implement undo and replay. Using the command pattern this way—actions as executable, reversible command objects, recorded to enable undo/redo and replay—is what cleanly enables undo/redo and action replay, encapsulating each action as a reversible, recordable object, which is far cleaner than ad-hoc undo and replay implementations. Use the command pattern to make actions undoable and recordable, encapsulating each action as an executable, reversible command object, and you cleanly enable undo/redo and replay through the recorded command objects.

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.

The command pattern represents actions as executable, reversible objects that can be recorded, cleanly enabling undo/redo (via the command history and each command's undo) and action replay (via recording and re-executing commands). Use it to make actions undoable and recordable.