Minecraft wiki entry for Horse_Update, associated text: Development began the month after 1.5.1 was released. Eighteen development snapshots were released, from 13w16a to 13w26a. During the development period, 1.5.2 was released. Several iterations of the fourth launcher were released during this time period, from 0.1 to 1.2.2. Nearer the end of the snapshot cycle for the 1.6 update, Mojang focused primarily on fixing bugs, rather than adding new features.