The number one thing that has been persistent in paper RPG gaming is a hesitancy to do anything beyond what is directly in front of them.
It's understandable. You spend four hours creating the perfect dungeoneer, or a character that is the epitome of your favorite story character, or a representative of the player in this world. The last thing you want to do is walk into total obliteration after 10 minutes of actual gaming. This is OK in video games, because you can quick save and restart if you die immediately.
And, say the PC has gained a few levels. You want to keep your characters alive because you have invested creation and play time in them. You aren't going to venture past what you know.
So, to encourage adventuring, you could come up with some sort of quick save device, so if the characters get killed they can always restart from the quick save point. Give them a special orb that let's them do this so it isn't totally out of game.
You could reward adventuring. First, nudge them to go off trail if they will not on their own. Reward them in a manner that makes adventuring an appealing thing. (If you have them go off the main story line and have them fight 100 orcs and the big treasure is a 50gp gem, they aren't going to be excited about going off main line.)
Tell certain players, outside of the game about treasure they missed if they had only looked around. When you see them making an effort to adventure, reward them.
There is an old fable, the wind and the sun were arguing who was more powerful. They made a deal that the next man to come along, whomever could get him to remove his coat would be the more powerful.
The wind went first. The harder he blew, the more the man pulled his coat tighter to fight the cold. The wind gave up.
The sun shown warmly and gently. The man removed his coat because he was comfortable.
The point of the fable is, the way to get people to do what you want is to motivate them with reward, rather than by force.