A 'normal' HUD is what Empires has. It isn't integrated into the game in a special way, its flat out slapped across the players screen like adhesive window decals. Dead Space has what is considered a 'HUD-less' HUD, meaning it isn't actually a HUD, but serves the same function. What would normally be integrated directly into the players screen is instead cleverly integrated into the players avatar and what that avatar uses.
so where would metroid prime fall within this spectrum? it is literally a heads-up-display but it is part of the character, not something slapped on artificially.
Metroid Prime would fall at the definitely a HUD end of the spectrum. HUD typically refers to some put directly on the screen. Good old RL HUDs used in aircraft are just info pasted on a magical pixie dust screen, putting it in a helmet is no different. (unless you have to sneeze)
This game is fucking awesome. I bought it the other day and I never thought it would be as long as it was. Feels too much like RE4 though. The weapons are fun to use, you can upgrade your suit for additional armour, the zero gravity bits are so fun. And ofcourse, the graphics are absolutely top-notch. EA have actually made a good game. And to think yahtzee didn't really like it. What a cock.
I believe there was an old jurassic park ripoff, where you played a chick, and she had a tattoo on her boob, you looked down and could see the tattoo [a heart] and it was filled up depending on health. Interesting example. Mmmmmmm. Boobies....