Emerald Cross v2.1 and Emerald Cross v3.5 are likely versions of the same Game Boy Advance homebrew game. Homebrew games are independently developed titles not officially released by Nintendo. These version numbers indicate updates and improvements to the original game.  Without further information, the gameplay style remains unknown, but it suggests a passion project by a dedicated programmer.

Emerald Cross v2.1

Elf - The Movie (U)(Venom)