“EFX” is a cancelled Virtual Boy action game by RevivalStudios, who are mainly known for their Vectrex and Videopac (Odyssey2) after market releases. The game described by the developer a “Z-axis scifi shoot’em up game, with a total of 8 levels and a bonus level.”
Only a single image of “EFX” exists. It was posted on RevivalStudio’s website in July 2011, showing an anaglyph 3D-rendered canyon landscape. It was deliberately vague as to “not spoil too much of the game” at that early point in development.
A physical release of EFX was planned for the end of 2012, but it was quietly cancelled, likely due to problems manufacturing Virtual Boy cartridges.