Somebody layed tiles over the concrete slab patio behind our house.

Bad Idea. These things redefine the phrase "Slippery When Wet".

First thing that comes to mind is to apply some sort of anti-skid to
them, but I have no clue what that might be.

Is there anything out there?

I'm resisting the urge to tear them up because:

- I have not idea how well the grouting or whatever
they are set in adheres to the cement below and,
therefore, how hard it will be to get a smooth
surface again.

- It's complicated by the fact that we had paving
stone sidewalks put in and, at the same time,
had the contractor extend the patio a little
on 3 sides with proper paving stones - so
whatever we replaced the tiles with would have
to be the same thickness as the tiles to match
elevation with the surrounding pavers.
--
Pete Cresswell