The game is played with the mouse.
Click on an item to search/take it. Each item takes a certain amount of time to be searched/verified.
Click "Mission" to see a list of the items you need to collect.
I don't want to say too much here, because I'd rather not spoil the game. Oh, please do play with the sound on if you can - while the sound isn't essential to finishing the game, it is kind of essential to the game's story.
If you enjoy the game, your support in spreading the word would be greatly appreciated - word of mouth is its best chance of reaching people.