Its an MMORTS (Massive Multiplayer Online Real time strategy game) meaning, you get on, build a few buildings, then AFK until those buildings are done. Currently, my VIllage Center 5 is going to take 7 hours total, and my Library 4 takes 2 hours. So, in the later parts, you simply start building then go do other stuff until its done. Though you can also trade with other players, build new settlements, and even raid barbarians and "luxuries". Its quite fun, and its still in the Beta phase!