You can end the ages without solving anything. What I found happened accidently:

1. Todelmer: upon arriving the first time, go down to the observatory. In front of the door, walk to the edge, turn around and look up. If correctly positioned, you can read those quadrant coordinates. BUT: if you now write the quadrant symbol (and this works for any of the quadrants) on the slate, you'll get the orbit sign immediately (and end the age without solving anything)...

2. Laki'ahn. At the windmill (opening the gates), lower the pedestal till under water.
Now, walk back to the main pedestal, step outside with the slate and write some strange/unknown symbol on it. Then return in the bubble and wait... The Bahro will take the slate to a new pedestal (as it can't drop it under water, and it can't return to the main pedestal ?!). Also: move the slate to the flooded pedestal. Again, write some gibberish on the slate and drop it in the water. Then link back to the main pedestal and wait for another symbol to appear.
I also got the Fish symbol this way, but I can't remember how I did that. I recall being in the windmill, playing with the gear and holding the slate at that time. And suddenly it was gone, and next I found the Fish symbol at the main pedestal.

I'm sure similar 'cheats' are available for the 2 other ages, but I'm not bothered

That is strange logic when seen from my end.

Why would someone pay for an adventure game and finish it within a few minutes.

If I had that kind of logic, I would just read a walkthrough and would not spend a penny for a game.