An acrostic is a poem (or other type of writing) in which the first letter of each line (or other recurring element) spells something out.
So, for this game, we'll be making acrostics using names. For instance, we might start out with an acrostic for Ben:
And then the next person would choose one of those names (let's say Neil) and make an acrostic out of that name:
...and so forth. Easy, right? Ok, so the first name is Zachary, and here is my acrostic: