Legionnaire

Similar to Crawford's earlier groundbreaking Eastern Front (1941) in terms of display and general gameplay, Legionnaire added a real-time computer opponent, and is one of the earliest examples of a real-time tactics (RTT) game.

In the game, the player takes the side of the Romans, playing the role of Julius Caesar and giving orders to their forces in real time. The computer plays as generic barbarian tribes, in blue, with the player's legions in pink. There are three types of units: infantry is represented by a sword, cavalry by a horse head, and Caesar's own Imperial Guard by an eagle. Orders are given to the units by moving a cursor over them with the joystick and then holding down the joystick button; existing commands are displayed as a moving arrow, and new orders can be entered by pressing the joystick in the four cardinal directions.

Chris Crawford wrote an early version of Legionnaire for the Commodore PET in 1979. This was a fairly simple game using character graphics and a limited amount of logic. He later ported this to the Atari 8-bit computers and released it as Centurion, but the game saw limited sales.

After writing Eastern Front (1941), Crawford was looking for ways to use the new scrolling-map technology introduced in that game. Avalon Hill had approached Crawford with positive comments about Eastern Front, and he promised to make a game for them. After three months of preliminary work, he started development in January 1982, delivering the first version in February and a final version in June. Crawford published an article on game design in the December 1982 issue of BYTE, using Legionnaire as an example.

Computer Gaming World in 1982 described Legionnaire as "a game that anyone can sit down and play without reading endless instructions or learning complex strategies". The reviewer stated that "the real time action in this game is my favorite point ... I know I'll be at the computer for an hour at the most", and concluded it was "as challenging as Eastern Front and immensely more playable". In 1990 and 1993 surveys of strategy and war games, however, the magazine gave the game two-plus stars out of five, calling it a "marginally historical simulation of Roman tactics".

Compute! compared the game to Eastern Front and felt it would "appeal to a much broader audience because the game is faster-paced, has fewer units to control, and is, therefore, a faster game." Softline called Legionnaire "a well-documented and thought-out program ... easy to learn and difficult to play well", with graphics that were "a fine piece of work", and concluded that "On a scale of 1 to 100, this is a 95".

Legionnaire was nominated for "Best Adventure Game for Home Computer" at the 1983 Origins Game Fair. Even as the game was being released, however, Crawford expressed his doubt that it would have the lasting power of Eastern Front. He later wrote in Chris Crawford on Game Design that he considered it competent, but "Neither the original version nor the Avalon-Hill version of the game was a great game ...certainly no masterpiece. It was good experience for me, but I would have spent my time better had I moved on to something that fired my imagination."

In 2013, Crawford publicly released the source code of several of his games, including Legionnaire.