Advanced Squad Leader is a tactical-level wargame that originally simulated infantry combat during World War II. It is a descendant of the original Squad Leader game, which was published in 1977, and it is known for its extensive rules and detailed gameplay mechanics. The game consists of modules that cover different theaters of the war, and players use counters to represent individual squads, leaders, and weapons.
One of the main reasons why ASL is so highly regarded is its level of detail. The game's rules cover a wide range of topics, including terrain, weather, line of sight, morale, and numerous other factors that can influence the outcome of a battle. The game also features a robust system for resolving combat, which takes into account factors such as the range, firepower, and armor of different weapons.
Another reason why ASL is so popular is its versatility. The game can be played as a standalone wargame, or it can be integrated with other modules to create larger campaigns. There are also numerous scenarios available, ranging from small-scale skirmishes to large-scale battles. The game system has also been extended back to the American Civil War and up to present day conflicts.
Despite its complexity, ASL has a dedicated following of players who appreciate its depth and detail. The game has been in print for over 30 years and has spawned numerous fan-made resources, such as scenario books and online forums. Overall, ASL's level of detail, versatility, and dedicated fanbase are some of the reasons why it is considered one of the most significant wargames ever published.
All you need to begin playing ASL is any one of the first four starter kits, each of which is a complete game though the higher the number, the more complex they are. Alternatively to start with the full system you will require the full rulebook and the first core module: Beyond Valor (both of which are available here).