Pixel-perfect sprites, rendered to a separate camera and blitted over the main screen. It is complicated if you just do it randomly. I find it's worth taking the time to write a really good sprite GUI before you start and then you never have to write it again. When I sat down with my current game ( not written in Blitz3D ) the first thing I did was write a really solid GUI system with various gadgets, as well as HUD items, horizontal bars, vertical bars, circular bars, HUD buttons, and HUD Overlays. You probably don't need at least half of that, but it is well worth working what you need and writing a nice reusable system to do it all in my experience.