Keyboard

Movement: Arrow keys - walk forward, backward, rotate left, rotate right
Enter/Return - open speech bubble to talk

Mouse
The mouse cursor changes depending on the action.

Arrow = movement and clicking on icons
Fishing rod = fish (fishing rod needs to be active in hand)
Exclamation mark (appears above cursor) = activate object

Left-click anywhere in 3D view to run to that location, clicking closer to the character is walk, rather than run. Moving the mouse will cause the character to rotate.

Left-click twice to place temporary marker (the character will run to this marker and mouse can be used without causing character to rotate)

Hold right mouse button and move mouse to change camera angle

Click on doors to open them and enter/exit buildings.