Just like Marvel Superheroes, DC got in the mix with a widely popular RPG... in my opinion much better than Marvel Suprheroes and probably one of the best RPG systems ever devised. Another member here on DRC and I use to kick around ways of adapting this system to the chatrooms like Marvel's FASERIP but it's very technical and doesn't translate well.
Saddly my DC Heroes collection isn't as impressive as my Marvel Superheroes, frankly cause no one parts with DC Heroes stuff and it all saw a smaller print run than Marvel Superheroes making it all extremely rare!
The First and Second Edition boxsets. The Third Edition is a book which has elluded me for years for a decent price.

Three of the RAREST books in the whole game. The Hardware Book is all about making equiment, the Magic book is all about playing mages like John Constantine and the Swamp Thing Source Book/ Adventure is a follow up to the Book of Magic!

The Superman and Batman Sourcebooks... along with an extra rule book from one of the boxsets. Always have extra rule books on hand for players to use as well if you can afford it or have access to multiple copies!

Wheel of Destruction, voted one of the best adventures in the game! Along with 2 of the 3 New Gods/ Darksied Sourcebooks!

The Bellevue Sourcebook, all about the Suicide Squad! Along with a Superman adventure featuring the android Brainiac and one of the many Who's Who of the DC Universe, which like the Marvel Universe Handbooks are rare and expensive.

Which this one features Batman villains and a huge technical detail layout of the Batcave with Norm Bregfoygle artwork! Note the Star Sapphire entry on the previous page. -laughs-

All in all everything you need to play the game and run some neat adventures well steeped in the DC Universe. I wish I did have more of this game's huge library of books!