Bump is a bit of a relic from the days where 99% of internet conversations came in the form of forums and typically has one of two purposes. By posting "bump" you are "bumping" the thread back to the top of the list (since most forum threads, at least back then, were sorted by most recent activity), or you're adding a comment so that when the thread is updated with responses, you'll be notified. Nowadays, in a non-forum environment or pseudo-forum environment (like this one), "bump" is a way to say "hey, I'm also interested in this question and would like an answer".
Hope that helps! I've only played for 25 minutes so far so I don't have the knowledge to answer your game question, sorry :(