Pet Rescue Saga level 29 is a tricky one, primarily because you've got to clear 99% or more of the blocks. That's a lot of blocks! You don't have a lot of room for error here, and there are a lot of tricky parts if you aren't planning on resorting to boosts. We'll do our best to help out, and see if we can get you past Pet Rescue Saga level 29 once and for all.
The top of the level looks like:
There are a bunch of balloons here, which don't really seem to serve any purpose. The game intentionally won't put any of the same color blocks on the screen, so you've just got to pop these to move on. It would be interesting if they were here for some strategic purpose, but in all my plays of this level I've yet to find any useful reason for detonating the bombs before they get to the bottom of the balloons. I suppose it satisfies that primal "bubble wrap popping" urge some of us get. But maybe I'm missing something - if you've found a good reason to do something weird here, let me know in the comments!
The overall goal up here is to break the glass and release the key so that you can drop any remaining blocks to the next level. I've not found any particular reason to pop the balloons or blow up the bombs in any particular order. I seem to always end up with two rows of blocks above the locks.
Once you've done all you can up top, focus on making big matches in the area below the key checkpoint. You need to charge up your rocket so that you can break the mesh and get the key down on top of the locks. Whether or not you can do this really depends on how well the blocks below the mesh are organized. If you can make some big matches, you can charge up the rocket in no time. The randomness of the colors means that you're going to have some false starts here, though.
A Mesh Breaker boost (the "wire cutter" looking one) can make short work of this entire problem, but you've only got a few of those for free and I'd suggest trying to conserve them if you can. King games are famous for putting you in situations where paying money makes your life so much easier though...
Once you've made it to the bottom, a whole new world of pain opens up. There is a lot of mesh down here, so again you might be tempted to reach for the Mesh Breaker again.
The center area is where it all goes down. If the blocks are arranged poorly here, they can easily form a checkerboard pattern that you can't match. Try to focus on matching small groups of blocks up high before matching blocks down below to try and mitigate this some.
As your rocket boost charges, make sure you use it! It doesn't do much good right at the end if you're already stuck in the checkerboard pattern, but it can be useful for clearing some of the mesh or wiping out some oddly placed blocks in the center platforms.
Again, this is going to come down to luck in a lot of ways. The colors of the blocks are all randomized, and if the pattern is bad, chances are you're going to get stuck.