I've completed the game as it currently stands (unlocked every building and completed every quest, except the bugged ones I mention below).
The quests "Find Suvi's Ring" and "Pay the Witch" appear to be impossible due to bugs. (I actually managed to click the correct square in "Find Suvi's Ring" once, but the quest still announced a failure.)
The Wizard's Tower promised me spells, but when I finally managed to build it I got nothing. I'm guessing that isn't implemented yet. (I did only build the Wizard's Tower in one area, though; getting the required artifacts is hard.)
The quest popups were annoying at the start, but eventually I got through all those pesky quests and... the levelup pings became the annoying part. It turns out that by the time you have enough income to be building in the later areas, you level up about once per second.