Choosing Between Unity's Input System and Legacy Input Manager for Multi-Platform Games

If your Unity project targets PC, console, and mobile, the choice between the built-in Legacy Input Manager and the package-based Input System determines how easily you can support gamepads, touch screens, and XR controllers—and whether players can rebind keys while the game is running. This guide compares the two supported approaches, highlights the trade-offs, and shows a concrete validation setup you can run in a fresh project.

The Decision and Its Constraints

You are deciding how your game reads player intent across multiple device types. The Legacy Input Manager is the default, axis-based system built into every Unity Editor installation. The Input System (com.unity.inputsystem) is a separate package that replaces axis polling with named actions and device-agnostic bindings.

Your constraints usually include the Unity version you can use, whether runtime control remapping is required, and how much time your team can spend learning a new API. The Input System requires Unity 2019.4+ for version 1.0 and 2021.2+ for version 1.5+, so older LTS lines may force the Legacy path unless you upgrade.

Supported Options at a Glance

Capability	Legacy Input Manager	Unity Input System
Installation	Built-in; works with all Unity versions, no packages required	Package com.unity.inputsystem via Package Manager; requires Unity 2019.4+ (v1.0) or 2021.2+ (v1.5+)
Configuration	Edit → Project Settings → Input Manager (axes and buttons)	.inputactions asset with action maps and bindings
Runtime rebinding	Not supported	Supported through the rebinding API
Device coverage	Keyboard, mouse, standard joysticks	Gamepad, touch, XR, PlayStation, Switch pre-built bindings
Code access	Input.GetAxis, Input.GetButton	Generated C# classes for type-safe action reads
Migration	—	Legacy wrapper allows both systems side by side
Performance	Negligible overhead	Negligible overhead; small allocation when enabling/disabling actions

Trade-Offs That Matter

Package dependency and learning curve. The Input System adds a package dependency and requires your team to learn action assets, binding paths, and the generated wrapper classes. The Legacy Manager needs no extra packages, but its axis model becomes cumbersome when you must distinguish between a keyboard key and a gamepad trigger for the same logical action.

Platform reach. The Legacy Input Manager does not support newer platforms like AR/VR controllers out of the box. If your multi-platform scope includes Quest, PlayStation, or Switch, the Input System ships with pre-built bindings that reduce per-device boilerplate.

Runtime rebinding. If players expect to remap controls from an options menu, the Legacy Manager cannot do this without custom platform code. The Input System exposes rebinding directly, but the rebinding UI requires the Input System's UI modules; omitting them causes missing rebinding screens and runtime errors.

Allocation behavior. Both systems have negligible CPU overhead for typical gameplay. The Input System introduces a small allocation when enabling or disabling actions at runtime. In most projects this is acceptable, but if you toggle actions every frame, consider pooling action objects or using the low-level API to avoid per-frame garbage.

A Concrete Validation Setup

To see the difference firsthand, create a fresh Unity 2022.3 LTS project and test both paths. The following steps describe a minimal validation; they assume you have write access to the project's Packages/manifest.json file.

Input System path

1. Open Window → Package Manager, set the registry to Unity Registry, and install Input System. Alternatively, add "com.unity.inputsystem": "1.5.0" (or a version compatible with your Editor) to the dependencies block in Packages/manifest.json and let Unity resolve the package.
2. When prompted, allow the Editor to restart so the legacy backend is disabled and the new backend activates. In an existing project, commit to version control before this step.
3. Create an .inputactions asset (right-click in the Project window → Create → Input Actions). Add an action map named Player and an action named Move. Bind it to a WASD composite on keyboard and to the left stick on gamepad.
4. In the Inspector for the asset, enable Generate C# Class and apply. Unity produces a wrapper such as PlayerControls.
5. Attach this MonoBehaviour to a scene object:

using UnityEngine;
using UnityEngine.InputSystem;

public class MoveLogger : MonoBehaviour
{
    public PlayerControls controls;

    void Awake()
    {
        controls = new PlayerControls();
    }

    void OnEnable()
    {
        controls.Player.Enable();
        controls.Player.Move.performed += ctx => PrintMove(ctx.ReadValue<Vector2>());
    }

    void OnDisable()
    {
        controls.Player.Disable();
    }

    void PrintMove(Vector2 value)
    {
        Debug.Log($"Move: {value}");
    }
}

Expected check: Enter Play mode, press W/A/S/D, and move an Xbox controller's left stick. The Console should print non-zero Vector2 values. On an Android build, touch drags bound to touch deltas should produce similar output.

Legacy Input Manager path

1. Open Edit → Project Settings → Input Manager. Confirm that Horizontal and Vertical axes exist (they are present by default).
2. Attach this MonoBehaviour:

using UnityEngine;

public class LegacyMoveLogger : MonoBehaviour
{
    void Update()
    {
        float h = Input.GetAxis("Horizontal");
        float v = Input.GetAxis("Vertical");
        if (h != 0f || v != 0f)
            Debug.Log($"Legacy Move: ({h}, {v})");
    }
}

Expected check: In Play mode, the same keyboard and gamepad inputs should produce logged values. Touch input will not appear unless you add custom touch-to-axis code.

Profiler validation

Open the Profiler (Window → Analysis → Profiler), record a Play-mode session, and toggle the Move action on and off repeatedly. Look at the CPU Usage and Memory areas. A practical threshold is to keep allocations from enabling/disabling actions under a few kilobytes per session; if you see per-frame spikes, investigate whether actions are being toggled inside Update rather than in response to state changes.

Limitations and How to Check the Result

Version floor. The Input System package has minimum Editor requirements. If your project is locked to an older LTS, verify the package version in the Package Manager before committing to the migration.

UI module dependency. Runtime rebinding screens fail without the Input System UI modules. After installing the Input System, confirm that com.unity.inputsystem and its UI dependencies appear in the Package Manager list.

Legacy gaps. The Legacy Manager has no built-in path for XR controllers or console-specific bindings. If your multi-platform target list includes those devices, budget time for custom plugins or plan to migrate.

Practical result check. Build a development player for each target platform (Windows, Android, and a console devkit if available). Run the same MoveLogger or LegacyMoveLogger scene and confirm that the logged values match across devices. If a platform produces no output, inspect the active action map or axis definitions for that device before changing code.