So first off, I'd like to propose that we do the ending credits of the game with overlay-text, instead of a cutscene, using a small level just for the credits. The music machf found, "MUSIC - SUMMIT VICTORY", can be played in the background. Potentially, we can try doing the credits with a bunch of scrolling textures, too, if we so choose... But anyway, the player will be both frozen in place and have the keyboard controls frozen, so all you're doing is just floating above this cool scene, watching the credits with the music.

I bet the credits might get a bit long - we can try throwing some other music in there, too.
What I'd like to see in this mini-scene: Waterfall; super-dense foliage, since FPS will be almost a non-issue; modeled terrain (rather than Trespasser quads); maybe a flying creature of some kind (or two) in the background; some quiet herbivores walking around randomly; random ambient sounds; a light mist; a skybox texture with the sun & clouds at dawn (from one of my many photos) (maybe even turning into day as you watch, if that's manageable).