Android
Main search for Virtual Reality: https://play.google.com/store/search?q=virtual%20reality&c=apps
By Michael Balzer. They are all fun in someway or another. None I would consider 7+ except the Catatonic video in the VRSE app.
7+
https://play.google.com/store/apps/details?id=com.google.samples.apps.cardboarddemo
https://play.google.com/store/apps/details?id=com.google.vr.cyclops
https://play.google.com/store/apps/details?id=com.shakingearthdigital.vrsecardboard
https://play.google.com/store/apps/details?id=com.cardboard360images.nyvr
https://play.google.com/store/apps/details?id=com.jauntvr.preview.tnf&hl=en_GB
https://play.google.com/store/apps/details?id=com.vw.vrcave
https://play.google.com/store/apps/details?id=com.disney.starwarshub_goo
https://play.google.com/store/apps/details?id=com.CedarFair.CedarPointVR
https://play.google.com/store/apps/details?id=com.VRCraftworks.Orbulus&hl=en_GB
https://play.google.com/store/apps/details?id=com.Creanet3d.com
https://play.google.com/store/apps/details?id=com.lunagames.jurassicvr
https://play.google.com/store/apps/details?id=com.mattel.vmnatgeowildlife
https://play.google.com/store/apps/details?id=com.mattel.viewmasterspace&hl=en
https://play.google.com/store/apps/details?id=com.mattel.vmdestinations
https://play.google.com/store/apps/details?id=air.com.ercangigi.sitesin3d
https://play.google.com/store/apps/details?id=com.company.aquariumvr
https://play.google.com/store/apps/details?id=com.drashvr.marsisarealplacecb
https://play.google.com/store/apps/details?id=com.company.nefertitivr
https://play.google.com/store/apps/details?id=com.eonreality.kingtutvr
https://play.google.com/store/apps/details?id=com.eonreality.magichapelvr
https://play.google.com/store/apps/details?id=com.eonreality.rollercoaster
https://play.google.com/store/apps/details?id=com.eonreality.eonexperiencevr
https://play.google.com/store/apps/details?id=org.androidworks.villagevr.villagevr
https://play.google.com/store/apps/details?id=org.androidworks.livewallpaperwatervr
https://play.google.com/store/apps/details?id=com.srbd.ml2fdt.vr.environment
https://play.google.com/store/apps/details?id=com.visitvr.cardboard
https://play.google.com/store/apps/details?id=com.doubledigital.fishschooling
https://play.google.com/store/apps/details?id=com.CorvusVR.TuscanyHD
https://play.google.com/store/apps/details?id=com.FabulousPixel.TuscanyDive
https://play.google.com/store/apps/details?id=com.JanRaacke.SpaceWalk
https://play.google.com/store/apps/details?id=com.VIRTUALIZAR.ScienceARVR
https://play.google.com/store/apps/details?id=cl.srcardboard.game
https://play.google.com/store/apps/details?id=cl.srcardboard.vidacelularvres
https://play.google.com/store/apps/details?id=com.lionsgate.Mockingjay2UKPremier
https://play.google.com/store/apps/details?id=com.Meta3DStudios.game
https://play.google.com/store/apps/details?id=com.Creativeworld.QuadcopterFXpro
https://play.google.com/store/apps/details?id=com.refugio3d.flightvrdemo
https://play.google.com/store/apps/details?id=com.silicondroid.galaxyvr
https://play.google.com/store/apps/details?id=com.lynxvr.SpaceShuttleTourCardboard
https://play.google.com/store/apps/details?id=com.Virtualitus.ArtGallery
12+
https://play.google.com/store/apps/details?id=com.otherworld.Sisters
https://play.google.com/store/apps/details?id=com.Dong3D.horrorhouse
https://play.google.com/store/apps/details?id=com.BDH.WarofWords
https://play.google.com/store/apps/details?id=com.converse.intheirchucks
https://play.google.com/store/apps/details?id=com.nivalvr.incell
iOS
7-9+
https://itunes.apple.com/gb/app/youtube/id544007664?mt=8 (Sadly this does not work try the following to view content from YouTube)
https://itunes.apple.com/app/homido-360-vr-player/id909196467
https://itunes.apple.com/us/app/in360tube/id977971797?l
https://itunes.apple.com/us/app/mobile-vr-station/id959820493?mt=8
https://itunes.apple.com/us/app/invr-for-google-cardboard/id983805476?mt=8
https://itunes.apple.com/us/app/solar-realms-rising-vr/id969896480?mt=8
https://itunes.apple.com/us/app/vrse-virtual-reality/id959327054?mt=8
https://itunes.apple.com/us/app/nyt-vr-virtual-reality-stories/id1028562337?mt=8
https://itunes.apple.com/us/app/eon-experience-vr/id944978838?mt=8
https://itunes.apple.com/us/app/legendary-vr/id1007098842?mt=8
https://itunes.apple.com/us/app/cedar-point-vr/id1023639387?mt=8
https://itunes.apple.com/gb/app/incell-vr-cardboard/id1044805956?mt=8&ign-mpt=uo%3D4
https://itunes.apple.com/us/app/skydive360/id1025171234?mt=8
https://itunes.apple.com/gb/app/dinotrek-vr-experience/id1018497986?mt=8
https://itunes.apple.com/us/app/vr-mojo-orbulus-special-edition/id998882503?mt=8
https://itunes.apple.com/gb/app/vanguard-v-for-google-cardboard/id1006371645?mt=8
https://itunes.apple.com/gb/app/inmind-vr-cardboard/id971720127?mt=8
https://itunes.apple.com/gb/app/flight-simulator-beenoculus/id952796420?mt=8
https://itunes.apple.com/us/app/discovery-vr/id1030815031?mt=8
https://itunes.apple.com/us/app/vr-playground-virtual-reality/id980153170?mt=8
https://itunes.apple.com/us/app/end-space-vr-for-cardboard/id1056999701?mt=8
https://itunes.apple.com/us/app/froggy-vr/id935702391?mt=8
https://itunes.apple.com/us/app/tuscany-beenoculus/id935275931?mt=8
https://itunes.apple.com/us/app/go4d-vr-space-ship/id954778682?mt=8
https://itunes.apple.com/us/app/shakedown-vr/id977660467?mt=8
https://itunes.apple.com/us/app/fov2go-tales-from-minus-lab/id503346367?mt=8&ign-mpt=uo%3D8
https://itunes.apple.com/us/app/space-coaster-vr/id1049464829?mt=8
https://itunes.apple.com/us/app/hidden-temple-vr-adventure/id1016417665?mt=8
https://itunes.apple.com/us/app/air-race-vr/id981838989?mt=8
12+
https://itunes.apple.com/us/app/sisters-virtual-reality-ghost/id957212695?mt=8
https://itunes.apple.com/us/app/insidious-vr/id989844820?mt=8
https://itunes.apple.com/us/app/war-of-words-vr/id944293466?mt=8
https://itunes.apple.com/us/app/bjork-stonemilker-vr/id1068948215?mt=8
https://itunes.apple.com/us/app/vr-tank-training-for-google/id999943714?mt=8
https://itunes.apple.com/us/app/dive-zombie/id903661452?mt=8&ign-mpt=uo%3D8
https://itunes.apple.com/us/app/virtual-kaiju-3d/id915447972?mt=8&ign-mpt=uo%3D8
https://itunes.apple.com/us/app/fasthit-vr/id943956895?mt=8&ign-mpt=uo%3D
https://itunes.apple.com/us/app/fractal-combat-x-fcx/id578085611?mt=8&ign-mpt=uo%3D4