I play on a touch pad tablet. This is surprisingly difficult, I tried easy mode and had problems with the 1st puzzle, but I overcame it, 2nd puzzle was easy, boss fight was impossible. Even with touch pad, I couldn't get to the weapons in time. Even if I did, I would be in a rhythm of always clicking the weapons. When I tried clicking the red exclamation points I found I had to be extremely fast, but going between the weapons and exclamation points at that low of a reaction time is nearly impossible. Then I tried Normal difficult, oh man that was a mistake. I couldn't even get past the 1st puzzle, the farthest I got was 3/4 of the air pump meter filled before the scarabs paralyzed her. I know you can rip off clothes to get them off, but that barely does anything in Normal difficulty.
If I am using a touch pad and I am having problems after numerous tries, how do you think a Mouse player will fair?
My suggestion to better this game is to increase the time it takes to be paralyzed in Normal difficulty and reaction time in the boss fights of all difficulty's.
I imagine getting the 3rd character means beating the game on both difficulty's and getting all achievements, but at this present moment that is extremely difficult and nigh impossible.