SDI
Also released as Global Defense (Sega Master System)
SDI — frequently asked questions
- What platforms is SDI on?
- SDI was released on Arcade, Commodore C64/128/MAX, ZX Spectrum, Atari ST/STE, Amiga, Amstrad CPC, Sega Master System/Mark III.
- When did SDI release?
- SDI was first released on April 1, 1987.
About SDI
SDI: Strategic Defense Initiative, or simply titled SDI and sometimes known as Global Defense. Players control a satellite and must destroy enemies by moving a crosshair over them and firing the satellite's weapons.
Summary via IGDB.
SDI on Wikipedia
SDI: Strategic Defense Initiative, or simply SDI, is a 1987 horizontally scrolling shooter video game developed and published by Sega for arcades. It was ported to the Master System, Amiga, Amstrad CPC, Atari ST, Commodore 64, and ZX Spectrum. Players control a satellite and must destroy enemies by moving a crosshair over them and firing the satellite's weapons.
Source: Wikipedia (text under CC BY-SA 4.0).
Game details
- Developer
- Sega Enterprises, Ltd.
- Publisher
- Activision
- Game modes
- Single player, Multiplayer
- Themes
- Action, Science fiction
Details via IGDB.
Every version compared
Prices, contemporary reception and the studio credited for each release
| Platform | Year | Loose | Complete | Sealed | Period reviews | Fake risk |
|---|---|---|---|---|---|---|
| Sega Master System | 1988 | $8 | $16 | $39 | 4 reviews | Low (look-alike) |
Also released on: Arcade · Commodore C64/128/MAX · ZX Spectrum · Atari ST/STE · Amiga · Amstrad CPC · Sega Master System/Mark III. We haven’t priced or authenticated those versions yet.
Collector value & authenticity
Sega Master System · PriceCharting sold data · Verified 2026-10-28
Other releases and variants
| Release | Loose | Complete | Sealed |
|---|---|---|---|
| European (PAL) release | $7 | $15 | $31 |
| Japanese release (SDI) | $22 | $40 | $90 |
How often it sells
- Loose: about once a month
- Complete: about once a week
- Sealed: about 2 times a year
Sales frequency from PriceCharting's completed-sale records, as of 2026-10-28.
Price over time
- Loose
- Complete
A loose copy sold for about $1.92 in Jul 2009, $7.14 five years ago, and $8.12 as of Oct 2026.
Show as table
| Month | Loose | Complete |
|---|---|---|
| Jan 2010 | $0.99 | — |
| Jan 2011 | $1.99 | — |
| Jan 2012 | $1.49 | — |
| Jan 2013 | $1.98 | — |
| Jan 2014 | $4.43 | $5.22 |
| Jan 2015 | $3.75 | $7.50 |
| Jan 2016 | $3.50 | $6.90 |
| Jan 2017 | $6.94 | $7.95 |
| Jan 2018 | $4.84 | $5.99 |
| Jan 2019 | $7.81 | $7.98 |
| Jan 2020 | $7.30 | $8.76 |
| Jan 2021 | $6.90 | $10.99 |
| Jan 2022 | $9.00 | $10.00 |
| Jan 2023 | $8.83 | $8.97 |
| Jan 2024 | $4.99 | $11.02 |
| Jan 2025 | $5.26 | $13.66 |
| Jan 2026 | $6.66 | $15.94 |
| Oct 2026 | $8.12 | $15.58 |
Monthly price estimates from PriceCharting's completed-sale records, sampled quarterly, through Oct 2026.
Release record
| Territory | Date | Product number | Known board |
|---|---|---|---|
| North America | March 1988 | — | — |
| Europe / PAL | March 1988 | — | — |
| Japan | 24 October 1987 | G-1338 | 171-5177 · MPR-11191 |
- Region
- NA+EU+JP
- Released
- 1988
- Authenticity
- Low
A modest Sega shooter that was called SDI in Japan and Global Defense in North America and Europe, and one of the cheaper US carts.
Global Defense is the Master System version of Sega's SDI, released in Japan on October 24, 1987 as SDI, and in North America and Europe in March 1988 under the Global Defense name. Computer Entertainer listed it among Sega's titles to watch for in 1988.
What the press said at the time
| Mean Machines Sega Issue 3 | December 1992 | OVERALL 80% |
| Sega Pro Issue 19 | May 1993 | 75% |
| Sega Pro Issue 20 | June 1993 | 75% |
| Sega Pro Issue 25 | November 1993 | 75% |
“Known better to arcade goers as SDI, this missile¬ blasting game has excellent graphics. The gameplay is addictive too - in fact the only thing wrong with it is the tricky control method, which makes it frustrat-ingly difficult to get into. If you're prepared to stick with it, there's plenty here. Try before you buy.”
“A freak accident has caused missiles from all over the worid to zoom off into space. You must blow them up. Simple, but effective.”
“A freak accident has caused missiles from all over the worid to zoom off into space. You must blow them up. Simple, but effective.”
“A freak accident has caused missiles from all over the worid to zoom off into space. You must blow them up. Simple, but effective.”
Also on other platforms
Arcade · Atari ST · Commodore 64 · ZX Spectrum · Amiga · Amstrad CPC
- Arcade. The arcade version uses a joystick to control the satellite and a trackball to control the crosshair.
Before you buy
Three releases exist: the US cart, the European cart and the Japanese cart, which carries the SDI name. The European cart is a little cheaper loose and about the same complete. The Japanese cart costs much more than the US one in both conditions, and it is a different, smaller shape that does not fit a Western console without an adapter. The US cart is cheap by Master System standards, and the look-alike risk is low. Make sure the manual is included on a complete copy.
SDI screenshots
Watch on YouTube
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