It's the little things in Metroid Prime 3 that really get to me. Well let me correct that, it's the little things in the entire Metroid Prime trilogy that get to me. From the beginning of Prime seeing the raindrops splash on your visor to the end of Prime 3 (I won't ruin it for you) I have been extremely impressed. Yes, there are major things in the trilogy such as incredible morphball puzzles, a genuinely unique way to control a first person game, and potentially the best boss fight of all time in Quadraxis, but it's the little things that make me truly love these games.
In the image below you will notice four blue lights, they look like little bars, at the top of Samus' visor. These little blue lights will change over time as you play the game to allow the user to know the battery power of your remote. You never have to leave the game by pressing the Wiimote's "Home" button to check on battery level, it checks that for you inside the confines of the game. No more breaking the fourth wall.
It may have taken me a while to figure this out but I was happy when I did. After playing through Metroid Prime 3 I noticed a set of four lights at the top of the visor screen that made no sense to me. When my roommate played the game two of the four lights were always blue with an occassional change to a single yellow light. The next night I was playing the game and noticed that my top lights were always set to a single yellow light with no flicker to any other color.
The last two Metroid games had a danger meter on the visor so initially I thought that's what this was. After another hour of playing the game the light changed to a red light with a battery warning a few minutes later. Then it hit me, Metroid is such an incredible game at immersing you in the environment that it even tells you when you (the player) is running low on battery. If you run low on battery, so does Samus. It's a simple thing, and most likely meaningless to some, but I found it to be an incredible added touch.
It is official, the Metroid Prime games are the most immersive games I have ever played. This was just the final straw I needed to make me see that.