I wrote a guide, you can download it from the home page. It says how to pass the first segment of the game. There is no guide for the second one yet, but there is not much content there, except for three new enemies, which are not so hard to find (not hard, I think so).
And all available costumes are at the first location, as a rule they are behind closed doors.
One of the suits is near the mutator “dash”, which is located in the tunnel under the horizontal elevator (Entrance in a huge hole, there aperture)
