I'm with pls8xx. I see no way to make that property flat, other than terracing, but it would still not be flat. Dogs need room to run, and that slope is cake compared to ours. Ours has chain link fencing all the way around it. We own beyond the fencing and there are two gates. We have several decks on our steep slope, and the decks are flat. There is some terracing, but even that is not flat. It would cost a fortune to flatten your yard. I think you should keep looking.

If that photo is representative of the area in question, then I'd reconsider using this extremely tight space for "outdoor living". And unless I am missing something, that slope is not very severe. Even if leveled, I doubt this area would be congenial to lounging outdoors or utilizing as a patio, etc. Too exposed and too restrictive and without sufficient space to develop any kind of green privacy screening. I'd consider just a mixed shrub buffer between you and the neighboring property, perhaps with a meandering pathway connecting it to more usable areas of your property. Unless that photo doesn't reveal the true slope of the area, I'd say no terracing or retaining walls are necessary or even practical. Can you post photos of other areas of your garden that may be more conducive to outdoor living/entertaining? I still think this is a situation where engaging a professional for an hour or two can be helpful - it is difficult even from the photo to get a good visual and a true sense of exactly what you are dealing with.

My yard did not have a steep slope, but I did want to avoid the slumping that the rest of the yards have been experiencing, so we put in some amount of "terracing" around the pool. The whole plan changed as we went along - first thing right away, the builder realized that we needed to drop the whole pool 4 inches. Apparently the city doesn't like the raised beam more than 24" high, so if it was higher, we'd have to get it engineered and a different approval process. Later we realized that the side yard was much higher than the backyard, so we had to add more stairs and another retaining wall. The whole thing was under $60K and that's with the expensive Artistic Shellock pavers and coping. If you click on my pool blog progress-in-pix and scroll down to the very last picture, it gives a good idea of how we dealt with the slope. Here is a link that might be useful: New Blue Pool Blog

Some thoughts on two projects: One: What is the most practical path from the point of origin at the house to get to your dock -- the path you now use ? Would that path begin at the corner of the house closest to the yard toys -- either a straight or curved path -- until you get to the toys and then from the toys beyond them to the dock? That walk path is where you should begin to create dirt steps about 4'-6' wide by using railroad ties strategically placed across the path as temporary small retaining walls to create level or gently sloping "steps" between the rail road ties -- digging to throw dirt above or below the railroad ties as needed. As you walk, you might take two or three steps on each dirt step you create. As you use the dirt steps you can see what steps work best and what steps need to be adjusted before you invest in blocks or stone for more permanent retaining walls for your grass covered dirt steps). Two: you might consider putting a retaining wall all along the lower point of the yard where you usually cease to mow -- below the hill. Literally dig a deep ditch for a footing/foundation along that line above which you cannot safely mow. You could then put rebar in place and have concrete poured into the ditch (BEFORE before you remove the dirt from below the ditch/concrete wall so the sides of the ditch can serve as a form for your retaining wall) -- before you throw any that dirt from below the ditch to above it. Once your poured concrete has set up, you can add a bock wall atop it, then begin to remove the dirt from below the concrete retaining wall to above the concrete retaining wall, adding other layers of concrete blocks to the wall as you are able to reach it from either above or below until you've achieved a reasonably level area both above and below the wall. You could then face the poured concrete with stone or brick if you choose.. DO make sure the bottom of the ditch you dig is lower that the ground level you want for the lower flatter area below the poured concrete retaining wall.. A ditch dug with a back hoe or other equipment will be wider that what you might dig by hand and take more concrete to fill but with the wider concrete wall you're pouring, you're building strength into your retaining wall. Do post some after pics to show us what you've done.