I don’t think Equestria has that kind of tech. At most, they might have super computers. {Giant hulking things.}
 
And they do have T.V., but not color yet. So, mid-1900’s tech on that scale.

There’s a lot of differences between arcade games and full blown computers.
 
Also, even though arcade games exists, doesn’t mean Twilight plays with them. For all we know she spends all her time studying.
 
Also, digital computers aren’t a prerequisite to arcade machines. It is possible to build an arcade game using basic mechanical and electrical parts. Many of the early arcade games were based off of relay technology. One reason we didn’t have arcade games sooner was the culture wasn’t there yet. It seems that pony culture is a bit more playful and as such would probably look upon a new game with more awe than we did.

@FanOfMostEverything  
But surely arcade machines are computer offspring?

Computers in Eequestria don’t look anything like that and are not called “computers” so she don’t know them like that?

Schizo Tech

Personal computers with graphic user interfaces and arcade machines are very different beasts.

PERSONAL computers might be alien-ish. As in, you know, being completely multi-tasking and such.
 
When you play an arcade game, its just a joystick and 3/5 buttons and you are not expected to know anymore than how to play the game.
 
A personal computer is far more complex than that.

You ever see those old Pong consoles from the 70’s? There’s your answer.