If you got yourself a PS Vita when they were relevant way back when, you'll be disappointed to see the state the machine is in now. Sony has discontinued production and support for the console, and the store is held on by a thin thread. But what if I told you that there is a way to revive your PS Vita into an active community that supports your Vita up to this date. This it the PS Vita homebrew scene, where the community has taken Sonys place. But to enter the Vita homebrew scene you first have to hack your Vita and install custom firmware onto the console. This might sound like a scary procedure, but it is quite simple and should not take more than 10min. But disclaimer, as with any custom of the record customization and modification it has a microscopic chance of permanently damaging your system, but it's worth it in my opinion as it would just be lying, collecting dust if it weren't for the homebrew on the system. If you want to hack your PS Vita yourself, simply follow the instructions on this website: https://vita.hacks.guide/.
Now that you've gotten yourself a hacked PS Vita, you can start downloading and playing with homebrew! You can try new games that are still being developed for the console, you can modify it to better suit you or you can develop your own games for the platform! To do this you could either make something completely custom using just C, C++, Rust or the likes. Or if you don't want to invent the wheel once again, you could use an existing engine like Unity or Unreal. I will be using Unity and guiding you through installing and developing on Unity.
First and foremost you need to have Unity and the PS Vita SDK files installed on your system. The SDK and required programs needed to develop with Unity are unfortunately Windows only, so the following steps will all be on Windows. I would follow this YouTube guide, but I have listed other sources on the bottom of this post. After you have installed the PS Vita SDK and Unity, you can start making games! (Btw, you can no longer use the PS Vita Unity license as it has expires, use must use the PS Vita & PS4 license). Before you start planning what you are going to make, I want to mention that I have never successfully gotten any internet connectivity to work when making games with Unity. This might be a problem with an easy fix, but I have not found it yet. Anyway, to start making a PS Vita game in Unity you just make a new project in the Unity Hub, and the first thing you do in that project is import the PS Vita Input asset. This sets up your project to use the inputs of the PS Vita.
To set up Unity for PS Vita development you want to first and for most change the build settings in the editor to PS Vita, with theise options selected:
You then want to press the "Player Settings..." button, and change the following settings:
You can change the icon here:
It's just important that your icon image is actually 128x128 pixels big, and that you shouldn't use any transparency in the image.
The other settings tab should be:
When you change the "Scripting Runtime Version" to ".NET 4.x Equivelant" you will need to restart the launcher, this is normal. And if you get any graphical glitches and bugs, it might be caused be the "Graphics Jobs", so just turn it off and see if that helps.
Now in the publishing settings tab you need to change the "Content ID" to something that isn't taken already. The way you do this is by going to VitaDB, and looking for a Title ID that isn't taken yet. So instead of having "IV0000-ABCD12345_00-0123456789ABCDEF" as your Title ID, it could be anything you don't find on VitaDB, but you place the Title ID where the "ABCD12345" part of the Content ID is. So if you choose the Title ID of just "555555555", your whole "Content ID" field in Unity should be "IV0000-555555555_00-0123456789ABCDEF" instead. You also change the short name to the title of your game and version and such as you would naturally think.
Another thing you can do to write some cleaner code is to use C# script defines, witch just means you can decide witch part of your code will be included when. So when I'm testing some code in the Unity Editor with a PS4 controller for example, I would use different input code than if I was to write the input code for the actual PS Vita. In that case you could write your code like this:
/// Code for the editor input
/// Code for the PS Vita input
Now that you have made something you actually want to try out on your Vita, then you have to build your project for the PS Vita platform. You just make a folder in your project directory named something like "Builds", and then you make a new folder inside here every time you make a build like "b1", "b2", etc. or "exp1", "exp2", etc. After Unity has exported your game into that folder, you just drag the folder on the "UnityTools.exe" program. It will then replace the folder with a ".vpk" file that you can install on a hacked PS Vita.
Just open "VitaShell" and press "Select" to use "USB Mode" so your PS Vita appears as an USB drive on your computer, and the you can just drag the newly created ".vpk" file into a folder like "downloads" on your PS Vita.
Then you just close "USB Mode" and press X on your newly imported file to install it. Congratulations, you have now developed and installed your very own homebrew PS Vita game! The only thing is that the game icon and such currently looks like ass. So how do you make your own custom design? Well you just follow this template for the design and add it to Unity in the player settings. (Btw, the images have to be 8bit, so you can just use this website to convert you images to 8bit color depth).
Now all you have to do left is actually make your game and keep in mind that the PS Vita is a mobile platform and don't make your game too intensive :)
PS Vita Hacking guide: https://vita.hacks.guide/
Unity for PS Vita guide: https://www.patreon.com/posts/guide-how-to-to-24906451, https://www.youtube.com/watch?v=7an4hSnJ9hM
Icon and LiveArea config: https://forum.hackinformer.com/viewtopic.php?t=765
Other Unity projects: https://www.psx-place.com/threads/vitaphobia-new-co-op-homebrew-game.34503/