I like the look of the game, especially some of the screens look awesome! Some others, for example when a bigger space has different shades, look a bit weird though, maybe you can change the colours a bit in Photoshop and try again? Otherwise it does look promising. If you can get a really good story together and add things that the player knows from the books/the movie, that game can become on of my favourites!
About the size: Don't feel too limited in the size. I don't know how much AGI can take, but if the graphics and the gameplay are great it would be worth some time downloading for me. It seems strange if the game is that huge, but if the quality matches its size, why not?
Zonkie