You will receive an 'Alternative Sound' bonus for use in the game per the following title(s) you own. ・Contra Anniversary Collection Link bonus: Retro Mix (Contra, Super Contra) ・Castlevania Anniversary Collection Link bonus: Vania Mix (Castlevania, Dracula II: Simon's Quest, Castlevania III: Dracula's Curse) ・Arcade Classics Anniversary Collection Link bonus: Konamix (music from previous KONAMI titles) Make sure to follow Contra: Operation Galuga for the latest news! https://store.steampowered.com/app/2235020/Contra_Operation_Galuga/