There are many different aspects to game play in Orion Sandbox Enhanced. Much like it's predecessor, the main game controls are as follows;
A (or left arrow) to move left or "west"
W (or up arrow, Space) to jump or climb ladders
S (or down arrow) to climb down ladders
D (or right arrow) to move right or "east"
Left Click on the mouse to use your selected item, place a "block" or to destroy a block
Right Click to use your selected item, to use an object or to get NPC details
The 1 - 9 buttons are slots used to quickly change your selected item in inventory
E to quickly open/exit the Inventory