So I’m interested in making a game Hunger Games like game which generates a new, different landscape every time you start it. How would I approach this? I would need need the middle of each map to be fairly flat and everything else to be random e.g. hills, mountains, lakes, forests. Could you provide me some examples or links that would help me? Maybe even help me start it. Thanks in advance 
You can achieve that by Noise Generation i think (For terrain). check out TerraNova : Terra Nova - Dynamic in-game environment builder - Released Projects - Unreal Engine Forums
For foliage . you will have to do random object placement . i myself dont know hot to approach that