can't help but note the lack of the word "Super" in the title. makes me think it might be something other than Super Castlevania IV. Maybe if you consider the Aria of Sorrow as CVI, Dawn of Sorrow port as CV II, and Order of Shadows as CV III, IV could be a new project (Order of Shadows II?) or port of anything (Portrait of Ruin??). it probably doesn't work that way, but it's a thought anyways.
EDIT: A quick google search of Handster and Castlevania reveals a page talking about Castlevania IV for Android that's from 2011. Seems like it's already out? Makes me wonder if it's a pirate version.
http://www.handster.com/castlevania_iv.htmlEDIT 2: Looks more like an illegal ROM now. Here's a link to Castlevania 1.0 (Dracula X) on Handster. Love it's description: "This is a SNES Emulator, and if you want the the default game "Castlevania", you can press the center button to download. The downloaded ROM is only taken as trial, please delete it afterwards or get the original copyrights on your own way."
http://www.handster.com/castlevania_castlevania.html?pos=1EDIT 3: I suppose it is possible that they offered Super Castlevania IV illegitimately at first, but now obtained a legitimate license for it after the fact? Things like that have happened before (ahem, Crunchyroll).