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SDI: Strategic Defense Initiative is based around classic-style shoot 'em up action. It puts you in control of a satellite which must ensure that the wave of bombs aimed for the United States do not hit. Direction of motion and direction of fire are controlled independently - on the 16-bit versions you rotate the mouse left and right to direct the targeting, move it up and down to increase the range, and use the joystick to move the satellite and thus avoid any contact.

Each level is split into defensive and offensive stages. On defensive levels you must stop each unit as it heads towards the earth, a lá Missile Command. Offensive stages follow the old 'shoot it before it becomes a danger' philosophy, being free-flying shoot 'em up sections among a network of destructible (but worth saving) platforms.


SDI: Strategic Defense Initiative SEGA Master System Title screen (US)
SDI: Strategic Defense Initiative SEGA Master System The beginning
SDI: Strategic Defense Initiative SEGA Master System Halfway to destroying the planet
SDI: Strategic Defense Initiative SEGA Master System Defend the planet against missiles

Promo Images

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Alternate Titles

  • "SDI - Now The Odds Are Even" -- Spanish title
  • "SDI" -- Official abbreviation
  • "Mobile SDI" -- Mobile Sega Ages title
  • "Global Defense" -- SEGA Master System title

User Reviews

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Critic Reviews

neXGam Feb 02, 2010 8.6 out of 10 86
The Games Machine (UK) Apr, 1988 81 out of 100 81
Computer and Video Games (CVG) Apr, 1988 8 out of 10 80 Jan 16, 2017 7 out of 10 70
Power Play Apr, 1988 6.5 out of 10 65
The Video Game Critic Nov 14, 2000 C+ 58
VideoGame Mar, 1991 2 Stars2 Stars2 Stars2 Stars2 Stars 40
Tilt Mar, 1988 8 out of 20 40
Game Freaks 365 2000 3.5 out of 10 35
Computer Gaming World (CGW) Aug, 1988 Unscored Unscored


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Martin Smith (66858) added SDI: Strategic Defense Initiative (SEGA Master System) on Jun 27, 2005
Other platforms contributed by chirinea (45076), Martin Smith (66858) and LepricahnsGold (128492)