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Play SDI (JP_US_EU edition) Online

SDI

Play Global Defense online on Master System. Aim a satellite’s weapons independently to stop missiles and enemy craft.

Browser play

Sega Master System — EmulatorJS controls

Default Player 1 keyboard mapping. Change keys in Controller Settings.

Console button	Keyboard
↑ / ↓ / ← / →	↑ / ↓ / ← / →
1 / START	X
2	Z

Open Controller Settings to configure your keyboard or gamepad. Touch controls are available on mobile.

How to Play SDI

Quick start

Press 1 or 2 on controller 1. First aim with the D-pad and fire with 2. Hold 1 only when you need to reposition the satellite, then release it to resume aiming.

Controls

D-pad: aim. Hold 1+D-pad: move satellite. Hold 2: continuous fire. For two pads, start on controller 2 with right+2 or left+1. Controller 1 then aims, controller 2 moves the satellite, and firing is automatic.

SDI — About this game

Global Defense separates the satellite from its aiming cursor. You must place shots ahead of moving targets while keeping the satellite clear of danger. Attack phases scroll through enemy formations; surviving threats bring a defensive response. Two controllers divide aiming and movement, allowing a partner to help protect the same satellite.

SDI Game manuals

Cheats

No cheats have been added for this edition.

Player verification and sources

Browser play was reviewed before this edition was published in the catalogue. The date below is the catalogue publication date, not the game’s original release date.

Browser test and catalogue publication date: October 24, 2026
Browsers and devices: PC: Chrome, Edge and Firefox. Mobile: Chrome on Android and Safari on iPhone and iPad.
Player engine and core: EmulatorJS 4.3.0-pre · segaMS
Tested by: rwEmulator

Sources and editorial basis

rwEmulator reviews edition metadata, release information, game manuals and first-hand browser-play notes. Available manuals are linked below; the editorial policy explains how facts are checked and corrections are handled.

Editorial policy and sources Trust center EmulatorJS player help