How to install this, and pretty much all romhacks.

1. Go into the XDelta folder
Double Click XDeltaUI.exe
Just to be clear, XDeltaUI.exe, NOT XDelta.exe

2. Under the Apply Patch Tab next to "Patch:" click open.
Click on your rom "PMD Explorers of Hell (V1.4).xdelta" or "PMD Explorers of Heaven (1.4)".

3. Next to Source File click open.
Choose your PMD Sky ROM. Make sure it's a clean version, and not Xenophobia.

4. Next to Output file click "..."
Choose your desktop/other folder you want the rom hack to be stored to.
Name the rom as you want and put ".nds" at the end. For example : "PMD Hell.nds".
Play the game on the desired emulator. 

5. The popular error message: "xdelta3: target window checksum mismatch: XD3_INVALID_INPUT" usually 
occurs when your Source file is not the required clean PMD Rom. 
It is possible that you are trying to apply a patch over an already patched file. 
To double check, try checking hash value as explained earlier.

If you need some help, here is where you can contact me : 
Discord : babou#0001
twitter : @babouzzz

