The RCT Technical Information Depot preserves fan reverse-engineering of RollerCoaster Tycoon file formats, checksums, encoding, object data, save files, track designs, and utilities assembled outside the game's official documentation.
The QBasic Games Directory survived the disappearance of its original home and returned at Phat Code, preserving a large database from the scene where hobby programmers made complete PC games in Microsoft's beginner language.
DAN-BALL started in April 2006 and still maintains a strange, durable catalog of original browser games, simulations, physics toys, comments, counters, and mobile ports.
The Duke Nukem Editing Project preserved tutorials, maps, and hard-won PrismEd knowledge for a game whose editing scene could easily have vanished with old forums and fan sites.