Axiom Verge is still coming to PS Vita. Pinky promise.
This is essentially the message that the game's creator Tom Happ gives in a recent blog post. He's hoping it will be ready by the end of the year but there are no guarantees on that.
The original plan was to get the metroidvania out on Sony's handheld this summer. But things went awry.
Mostly, the delay has been caused by Mono never being ported to PS Vita. Happ was relying on this happening so when it didn't he was stuck. Luckily, another solution was found.
Sickhead (the developer of Monogame) started developing a C# to C++ cross compiler. This meant that Axiom Verge (and TowerFall) could be ported to PS Vita but it's a lot of work.
Sickhead is currently working on Axiom Verge's PS Vita version but sorting out the executable size, memory usage, graphical complexity, among other difficulties is taking time.
Oh, and Happ also gained a son recently (congrats!), so he's been on paternity leave. But this hasn't directly affected Axiom Verge's delay.
That's all for now but once we hear more about Axiom Verge on PS Vita we'll ensure you know too.