.. General Game Info
This is a classic (not to say retro) point-and-click game. In the PC version, when you want to look at something, right-click on it; when you want to interact with it (pick it up, talk to it, use it), left-click on it.
In the mobile version, touch the person or thing you're interested in, and two icons will pop up: a hand and a magnifying glass. Choose the magnifying glass to just look at the item and the hand to interact with it. This includes people; if you want to talk to someone, touch them and choose the hand icon, as intrusive as that might sometimes feel.
Click/touch the top of the screen to see the menu, which contains the notebook, your inventory, and the Options menu (where you can save and load games). Notice that as with the first two games, the settings you can adjust are really minimal; you can't change the volume levels or turn the music off. It should also be noted that in the PC version, pressing Ctrl-Esc during the game will drop you to the desktop, but the game will be chucked when you come back. If you need to check something on the desktop, it's better to save your game and close it, then restart and reload when you're done.
In this game, you can switch between being Rosa and being Joey. To change from one to the other, pull down the menu and click on either R or J to switch. Notice that Joey doesn't have an inventory (d'oh!).