The Lost Reels on Android and iOS
Adapting light-gun series for use on a touch screen doesn't sound immediately appealing, but I'll try most things once. After all, The House of the Dead: Overkill was enjoyable for what it was back in 2009 on the Wii. Following a more recent "Extended Cut" release for PlayStation 3, Sega has now turned to the mobile market with The Lost Reels.
This iOS and Android title has of course incorporated in-game currency alongside real-world money. The $4.99 download includes two "movies," both of which consist of four levels and a boss encounter; a third movie can be bought for an additional $1.99. Can't say I'm expecting too much out of this adaptation, but tapping to kill zombies could conceivably be stupid fun.