It sounds like you're referring to a for METAL SLUG 3 on a PlayStation Vita or a compatible emulator (since PCSE00665 is the Vita title ID).
You can connect with another Vita user nearby to play the full game together, just like in the arcade. Download METAL SLUG 3 -PCSE00665- -v01.00- .vpk
is a commercial product owned by SNK Corporation . The PS Vita version is available for purchase on the PlayStation Store (where it remains playable on PS4, PS3, and Vita, though the Vita storefront is now legacy). It sounds like you're referring to a for