I would go for a small cubby house a swing / slide and maybe a small trampoline

You could have a small veggie garden, or a cubby house, or a sandpit.

Tricky one… I would pave an area big enough to ride scooters and bikes(now or in the future depending on kids ages) mini trampoline at the furthest end. You can tape a hopscotch onto the pacers too and nail a chalkboard to the fence or house. You could have hanging veggie patches or flowers (again from the fence or house) I guess it really depends on exactly how much room you have.

I’d recommend searching on Houzz.com as they have a lot of backyard area ideas and you can narrow the search by specific categories, like small or narrow yards. Maybe think about a chalkboard hung to the fence for them as then it won’t take up much of a footprint in the garden but gives them a play area in a small space.

you can get pots that hang on your fence so you can have greenery without comprimising on space. the kids will love it but the littliest one won’t be able to play in it.

Play area and a garden area. Lots of nice little areas for different garden activities.

A small veggie,strawberry patch would be nice.A princess cubby house & a lovely mandarine tree or your child’s favourite fruit would be nice to grow.A paved area & a table & chairs & barbecue area would also be nice.Some sweet peas growing up the fence & some other flowering plants would be nice,maybe a fairy garden in a spot.

More kid friendly as our house is small too so somewhere for them to play

Do you want to make it kid friendly, adult friendly or a bit of both? I would probably start with kids stuff and add from there