Games for portable consoles like the Nintendo 3DS and the PlayStation Vita make for natural ports to mobile hardware, if only because the technical requirements for those games are only a fraction of the hardware power needed for full console titles. LEGO has already released several of these, and the latest is in the company's home-grown line of vaguely Asian-style action toys, Ninjago. Shadow of Ronin is an action title that stars the characters from the kids TV show and the building sets, and it's available for five bucks with no in-app purchases.
Like most "full-sized" LEGO games, Shadow of Ronin has you running around various 3D stages, busting up bad guys, grabbing collectibles, and "building" the various components you need to progress. Several of the show's characters are available to play, each with their own weapons and skills, though the actual mechanics don't change much between them. Levels are spruced up with occasional mini-games and vehicle sections. The game's story is fully voice-acted (not always a given with portable games) and ties in with the surprisingly deep lore of the TV show.
LEGO games tend to be pretty good, at least by the low standards of kid-focused titles, and Warner Bros. resists the temptation to fill them with in-app purchases. That makes them a safe bet for parents who want an acceptable mobile game without the fear of a giant credit card bill.