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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 ZX Spectrum Ready to start
SDI: Strategic Defense Initiative ZX Spectrum Results - with double-points for perfection
SDI: Strategic Defense Initiative ZX Spectrum High scores
SDI: Strategic Defense Initiative ZX Spectrum Level results

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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

Sinclair User Feb, 1989 90 out of 100 90
Sinclair User Jul, 1991 70 out of 100 70
Crash! Jul, 1991 70 out of 100 70
Your Sinclair Jul, 1991 64 out of 100 64
Your Sinclair Mar, 1989 6 out of 10 60
Crash! Feb, 1989 59 out of 100 59
Computer and Video Games (CVG) Jul, 1991 59 out of 100 59
The Games Machine (UK) May, 1989 37 out of 100 37


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Martin Smith (66801) added SDI: Strategic Defense Initiative (ZX Spectrum) on Jun 27, 2005
Other platforms contributed by chirinea (44086), Martin Smith (66801) and LepricahnsGold (128247)