Well you first have to go through the tutorial mission in a specific order. The tutorial sort of teaches you gameplay in a chalenging way. I quickly gave up because I couldn't get past the second chalenge. This is pure platforming still. I asume the sneaking comes later.
What I would like to see:
I can skip the tutorial mission.
Inside the tutorial mission I can do any chalenge in the order I want, like the TDM training mission.
The chalenges should be more like learning materials. Not too difficult for new players.
There's guide's in text form that are very big text boxes. If you have your resolution set high you almost cannot read them (font is too small, but cannot be changed). So I set the resolution lower (1280x720 I think, while normaly I use 1920x1080).