I probably should have looked at it more in depth, sorry.
core.aslx is included in all games, which is likely why trying to add it to the game yourself is giving you an error. ASLX scripting doesn't change between the different modes, all that changes is the editor interface.
I don't believe there is a default scoring system, but all it is is a variable so it's really easy to add your own. Somewhere in the beginning of the game I would add the line:
game.score = 0
Then in each room, just have the line:
game.score = game.score + 1
That will increment the score variable every time you enter a room. Then if you just want to display the score at the end, you'd use something like this in the description of the final room:
msg ("Your score is " + game.score +" out of XXX")
Where XXX is the total number of rooms. You could write some code to automatically calculate the number of rooms, but if you want to keep things as simple as possible, just keeping track yourself will work fine.