There is only one file type that uses the .LGT extension:
Let's Go! Theme File
Settings file used by Let's Go!, an arcade-style game where players dodge oncoming blocks; contains graphics that are overlaid on the game interface; used for customizing the look and feel of the game.
LGT files can only be used by the paid version of Let's Go!. They can be created using the Let's Go! Theme Compression Tool (LGCMP.exe), which can be downloaded from the Let's Go! website.
NOTE: Let's Go! and Let's Go! Theme Compression Tool have been discontinued and are not available for download.
Updated: December 31, 2016