Great guide, I'm working on this game right now.
This game is not so good, not so bad.
It's a "just for fun".
I have a suggestion for this:
Headlong into Monsters
Kill 6 enemies in one ram attack
I think that this achivement is very easy on the side-scrolling section (particularly the Phase 2 side-scrolling section) because you don't have to worry about the "third dimension".
Edit: finally got my 1000/1000 today.
The "Shadow of the Wickerman" arena give me some trouble because of the damned blue enemies that cut my arm off in one hit.
And the game that frozes my X three times doesn't help!
Still a very fun game! Can't believe that it's so underestimated.