A few of my favorites:
-Shovel Knight - Must have if you're a fan of old-school platformers. This one mixes DuckTales with RPG elements and an excellent soundtrack for a very fun experience.
-The Incredible Adventures of Van Helsing - If you like hack-n-slash RPGs like Baldur's Gate: Dark Alliance, then this one is a lot of fun to play through. It sets itself apart by being in Victorian England and having a monster/evil theme rather than a medieval theme like most games of this genre.
-Bionic Commando: Rearmed - If you like the original NES game, then this is more than worth playing through. It's a fully updated and modernized version of that game.
-DuckTales Remastered - There is a physical version of this, so I don't know if you really want it. But if you do settle for digital, this game has all the fun of the original with better graphics and a bit of fan-service added. As well as extra end-cap levels!
-Bloodrayne Betrayal - I've only actually played the demo of this. But the next time I have some XBox Live credit, I plan on picking this one up. It's a Metroidvania-style hack-n-slash platformer, but with more focus on the action side of things.
-Dungeons & Dragons: Chronicles of Mystara - This collects the two beat-em up arcade D&D games. It has some great, eye-popping 2D graphics. And it mixes RPG-elements into the beat-em up gameplay making for a much more satisfying experience.
-X-Men: The Arcade Game - Just some fantastic, old-school, Konami beat-em up action that you can team-up with friends on. Play as the 80s X-Men and fight your favorite mutant villains.