The scene is not the same art style of the game at all - I just threw in some mountains and sunset to see what it would look like when moving around. Use the WASD keys to move and the mouse to look. You may have to click on the file first to activate. I recommend clicking and holding the mouse down while moving it around so Flash still picks it up when it's out of the bounds of the swf. Otherwise your view won't move when the mouse is out of the scene.
The prototype is slightly disorientating when you move around because although there is a horizon line, it's not always in view and large areas are just gradient colours. The game will actually have a lot of detail in the levels to help keep the player aware of which direction is actually up.
Games like the first Alien vs Predator were particularly nauseating for some when playing as the alien. There was never any sense of up and you sometimes had to just let go of holding the wall (you can crawl along any surface, wall, ceiling, etc.) to see which way you fell down. There may have been a subtle indicator but I can't really remember, certainly if there was it wasn't accessible enough in the heat of battle.
Google is being mean to me, so here's a shot of the latest game (currently in development) with alien perspective. Just smear wax on your screen, colour in the glossy highlights and make everything a lot less rounded and smooth and you'll be able to imagine what the original game looked like.
I've been thinking on what sort of elements can be included in the levels. Slopes have been giving me pause. I could easily put in any surface if I have a fully dynamic animation system (the character will lift feet over obstacles, lean forward going up slopes, and so on) but that would also be a huge slowdown for Flash. So I've decided to to a semi-dynamic approach. I'm going to build an animation editor that uses inverse kinematics to animate the various poses - the game will then use those as standard animation (similar to frame based animation). I'll have to write a blending system so the various animations (walking to jumping to running) blend smoothly between each other instead of just flipping into the next set of frames in a jagged manner.
On top of this, the arms and head will be fully dynamic. This is so the character's head can look towards the mouse cursor and the arms can aim, hold the gun, interact with objects. Should the arms not be doing anything much, they will follow the suggested animation (like swinging in time to the legs when walking). This is still quite an intense (processor-wise and the programming of it) animation system so I might have to scale it down but for now I will have lofty dreams.