To beat level 29, you need to focus on clearing out the central part of the field as this will give you the room to play and create power-ups. By the way, not all crates hide golden tiles underneath so there’s no need to destroy all of them.
Also, do not rush into using power-ups — try to get a couple of them close to each other and then explode them all at once! This will clear out more tiles and charge the Lightning power-up faster.
Check out this video that shows how we got through level 29.