Their belief was the wargame "industry" was far larger than their rival, Avalon Hill, thought it was. And they were right. As they exploded onto the marketplace they used the Strategy & Tactics Magazine to propel their wargames by including a game with each issue. The use of the magazine helped in advertising the games and the company, which, in turn, helped in advertising the magazine and the company.

As the magazine became more of a military history magazine, they began publishing Moves Magazine in 1972, which carried game-related material, although the games remained in Strategy & Tactics Magazine.

The games, nearly all military in some form (whether historical or not), ran the gamut of history and near-future history. While many were based on small, mostly obscure battles, they did have the occasional "monster" games like Wacht Am Rhine and Terrible Swift Sword.

One trademark of SPI, when they began publishing "boxed" versions of their games, were the flat, plastic "boxes" with built-in trays and see-through, clear covers.

Even though SPI did get to a parity with Avalon Hill, the wargame market was beginning to wind down, and in 1982 SPI went out of business. TSR picked up the assets and republished some of the games but the wargame market was collapsing and this did not last long. Many of the ex-SPI staff went to Avalon Hill and set up Victory Games to produce wargames.