Battle Line is a 3-card poker game by Reiner Knizia. Although it is published by a wargame publisher, GMT Games, the theme is shallow and basically a two-player poker variant. It is a short but tense game of risk and hand management.
The game plays like this. Each player starts with a seven-card hand from a 60-card deck composed of six suits, ranging from from 1-10. A battle line is formed by placing six flags. On your turn, you play one card to a flag, face-up, then draw a card from a common draw pile. When three cards are played on a flag, it is be compared against the three card hand on the opposite side of the flag, for capture.
If the opposite side does not have three cards, the game continues. However if a player can prove that her three-card hand cannot be beaten because essential cards to form a stronger hand are already in play, the flag is captured. Victory is achieved by a breakthrough, capturing three adjacent flags, or by overwhelming -- capturing five out of the nine flags, anywhere on the battle line. The poker hands are ranked as follows: Straight flush (three of a kind, same suit) > three of a kind > flush (same suit) > straight (consecutive) > summation.
Battle Line is a reworking of a previous Knizia game, Schotten-Totten. The primary difference is that Battle Line adds an additional draw deck -- Tactics cards -- and uses a seven- rather than a six-card hand. Tactics cards are war-themed events that expand strategic options. The events are mostly exceptions to the game rules, allowing players to break or change the poker hands.
The official Battle Line iOS universal app by Gourmet Gaming offers both Battle Line and Schotten-Totten style of play with a cunning AI. The free clone, 3-Card Brigade Poker by Mpowers, offers Schotten-Totten style of play. The 3-Card Brigade Poker is available for online play, or as an iOS universal app, and a Chrome (offline) browser app.