A collection of all the Famicom AND NES games by Technos Japan starring their "Kunio" high school character, plus the three NES Double Dragon games. You can opt to play the games without the original hardware's excessive sprite flickering and stuff ("QualityUp" versions); although this is a Japan-only release, the Collection's menus are all in English.
As far as I can tell/remember, the games play great; this collection is a real treat. I'll admit that for the most part the Kunio games are just a bit too wild and crazy for me to hang with--and I'm intimidated at the thought of trying to get through River City Ransom, but maybe I'll work up the dedication for that *some* day--but even the ones I downright dislike are at least interesting to check out. And the first two Double Dragon NES games are STILL great beat 'em up fun, even if you can't continue : P (actually have to get good, I guess, ack!).