One of the many announcements that came out of Google I/O this year was Google Cardboard for iOS devices. If you're new to the idea of Google Cardboard, just imagine if you took an Oculus Rift but distilled it down to its 5th grade science fair basics and cobbled together a cardboard holder for both your phone and a pair of lenses to create a barebones VR experience. There's a number of places selling them for between $20 and $30, which still feels a little expensive to me for quite literally a piece of cardboard and a pair of plastic lenses. This is apparently the one they gave away at Google I/O if you want to specifically get that one.
Anyway, assuming you've got Google Cardboard and an iPhone capable of sliding inside of the apparatus, you should give Hidden Temple - VR Adventure [$1.99] a look. They've got a trailer that seems pretty neat:
And here's a tutorial showing how all the VR stuff works:
I'm not super sold on the idea of VR games just yet, as the few I've tried for Samsung's Galaxy Gear seem supremely basic. Calling them "games" sometimes even feels generous when they usually feel pretty similar to the typical VR tech demos out there, but slightly more interactive. If you've got the hardware to check out Hidden Temple, you'll have to let us know if it's cool enough to drop $20 on literal cardboard.