Life can be harsh on the open prairie--food is often scarce, or at least patchy, and there aren't a lot of natural defenses to protect your city from predators or rival nations. Fortunately, your 2 Scouts can cover a lot of ground looking for flocks of wild turkey or herds of deer. Prairie is a wide-open map, with only a tiny bit of water offering slightly more protection than your average Arabia. The big difference is in the allocation of resources.
Each player has 2 puny berry bushes near their Town Center. All other food must be caught on the hoof. There are large patches of deer, boar and turkeys scattered about the map, but you are going to have to leave the safety of your Town Center to locate them. At least the initial berries give your villagers something to occupy their time while your Scouts charge around the area looking for more food. Later on in the game, wood becomes the limiting resource, and battles may occur over the copses of trees.
Don't think for a moment that this hunting and gathering lifestyle leads to a slow or boring map. Rather, you actually have a lot of interesting options starting out. Will you construct your first Mill far from home? Will you try and pull off some Scout raiding on enemy food camps? Will you kill off his deer with archers? Prairies promotes multiple towns, so even if you can't easily defend one of them, there are always others to be had. Obviously Mongols, with their great scouting and hunting bonus, are a good draw on this map.
As a suggestion to custom Random Map designers, Prairies shows that often subtle changes to resources or water terrain can have big ramifications for gameplay, particularly in the opening moves.
Thanks to Jon Peters, ES programmer, for designing this map and for those fans and fansite webmasters who joined Mike McCart in Denver helping to test it!