Metal Gear Solid: Peace Walker

[LunaMoo]

Works fine here
   

So I would guess your problem is either due to:
- using a device with really buggy graphics drivers,
- enabling hack which disables stencil test or some other hack/setting which simply breaks stuff in this game.

In the latter best just restore settings to default(option for that in system settings) and for the future maybe stop enabling options you don't understand. Some emulators, unfortunately including ppsspp do have a lots of game breaking settings, kept for very specific needs or by popular demand, activating options just because they exist is NOT recommended.

If it's your device problem trying different graphics drivers could help, but there's probably not much else to try.