Listing of Extra Games Unlocked by In-game Achievements
Titles contained within Collections and other Bundles can be listed as included by displaying links on the Game Page to each respective title's own page. However there is no current way to list titles unlocked as secrets from earning achievements or other various tasks in game.
Ex. Completing the Xbox release of House of the Dead III unlocks House of the Dead 2.
Re-worded for clarity.