From Creative Computing
Encounter! is a game played in real time. Moves are accepted from the players independently, as fast as they can be typed. So Encounter! is an entirely different type of game than Chess, where moves are made alternately. There is no time for lengthy consideration of your moves.
The board in Encounter! is divided into districts...A district may be empty, occupied, or blocked. Empty districts are represented by spaces, and occupied districts by the number of men in the district. Blocked districts, which serve as obstacles in the game, are shaded in. At the outset of the game, each player sets up his portion of the board, while the other player leaves. Thus, the players do not know the other player's initial setup until the game actually begins.
The object of the game is to wipe out all the opponent's men, or his home district, depending on the particular version of Encounter! played.
Encounter! is interesting for being one of the first-ever commercial video games and for being (perhaps) the first-ever "real time strategy" video game. The game play area was a grid with each square (called a "district") receiving a letter designation (columns) and a number designation (rows).
Commands were received simultaneously for each player via two keyboards. Allowable commands included "M" (move), "T" (transfer), "A" (attack), "X" (stop attack), and "D" (set values for attack). For example, "A A12 B12" would indicate an attack from A12 into an adjacent (enemy) district, B12. Attacks between districts were handled by the computer; the players could see the results immediately.