Plenty of potential. I would look around for some construction sites that have concrete debris or, simply go rock collecting. In my backyard my unfinished course is made up of concrete rubble and debris, along with river rock.
@WickedFog or
@Tunedfrog had suggested to pile up some stuff and use a burlap mesh or chicken wire to lay down and then skim coat it with some mortar to make hills and obstacles. Correction:
@Tunedfrog suggested leave it loose to change it up if needed;
@WickedFog suggested using mesh or wire with a coat of concrete or mortar.
Rock and debris collecting is a lot of work trust me; my little truck doesn't carry much in one load either, but well worth it once it starts to take form.
You have a pretty good-sized area, looks to be perfect for some minis too.