i make an effort to get through it every 4 or so years. last year (my third attempt) was easily my most successful one. i suspect I got through 40% of the game. in the past, i'd bounce at the first RTS segment. still can't finish it though. I like everything about it conceptually. playing it is a whole other issue.
They really don't. They have all the hallmarks of being drawn directly into a paint program. The gradients, the little details, it all points very clearly to being pixel art I'm afraid.
That doesn't mean there wasn't some concept art, though.