Here is the full list of all 8 Shtriga: Summer Camp achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Completed a mini-game in less than one minute
Completed the game without using a single hint
Completed every mini-game without skipping any of them
Found every item in a hidden object puzzle without using a hint
Found every item in every hidden object puzzle without using a hint
Played the game for more than one hour straight
Watched every video
Complete "Shtriga: Summer Camp"