OK, so the basic premise for Retro Game Challenge is that it's a compilation of clones of famous games from the 80's. By completing certain challenges in these games (you can figure out what the game is a clone of based on its release date and, you know, actually playing it), you can then unlock new games. As for the clones, there are some pretty good ones, like the Galaga and Ninja Gaiden clones.
So, there's the variety that kept me coming back. On top of that, these clones are very well done. They don't feel like they're inferior to the games that they are imitating and are just downright fun. Rally King, people. RALLY KING!
Another cool feature of the game is the magazines. When unlocking new retro games, you also may find yourself unlocking fictional game magazines. These are chock full of goodies, though, as not only do they provide cool insights into each individual retro clone, but also developer interviews and cheats that will actually work in the games. In the Contra clone, the actual Contra code works. Pretty cool, huh? I think so!
With each of these games, Retro Game Challenge managed to maintain a steady level of interest in myself. The build I played was the full-on Japanese release, which has been on Japanese retail shelves for about a year. So, I was able to check out each of the games. In combining all of these different genres (there's even a full-fledged RPG in there that, supposedly, offers up many hours of entertainment) together into one DS game, anybody would be crazy not to pick this up. The addition of challenges makes the replay value skyrocket, as not only do the different experiences of the genres offer up an incredibly unique package, but the different challenges within each of those specific titles provides another layer to make this one of the most enjoyable experiences I've had on the handheld. And, for a system that is known for having unique and wonderful titles, that is saying a lot.