The first #: engine version(1+)
Second #: Release stage (1=Alpha, 2=Beta, 3=Pre-classic, 4=Classic, 5=Legacy, 6 - 9=finished game) Last #: game version(0-2)
v1.4.3 is an classic of version 3,
with version 1 of the Terrain Simulator engine.
(BTW, feel free to use the engine from any version in your projects! Just give me credit when it's shared)