System i Leg, which translates to System of Play, was the natural progress of LEGO Mursten and is the foundation of L:EGO sets today. Designed by Godtfred Kirk Christiansen who organized the existing LEGO Mursten sets and modeled new designs around a single, common theme - a townscape or street scene. After nearly a year of development the result was the LEGO Mursten System i Leg (System of Play). The System i Leg was unveiled at the Nürnburg Toy Fair in February 1955. The original Automatic Binding Bricks sets and then LEGO Mursten sets were continued to be manufactured under the System i Leg theme.
1955 LEGO Sets
1955 was a very important year for LEGO. In this year, Godtfred Kirk Christiansen attended both the attended the London and Nuremberg Toy Fairs where he eventually came up with the LEGO System of Play and the now classic Principles of Play. These principles were issued to every LEGO employee in 1962 and still stand as the core principles of the company. Godtfred organized the existing LEGO Mursten sets and modeled new designs around a single, common theme - a townscape or street scene. After nearly a year of development the result was the LEGO Mursten System i Leg (System of Play). The System i Leg (System of Play) was unveiled at the Nürnburg Toy Fair in February 1955 but the reaction was less than positive.