The fundamentals of Bloom Town are simple: Each turn, place one of your two building tiles in hand on your personal game board, score points for the tile, then pick up a replacement tile from the town square board.
The complications start once you get into the details, such as your replacement tile being dependent upon where you played the building tile on your turn. Cover a tulip bulb on your board? Then you must pick up the tile from the tulip bulb space on the town square board. Want a different tile? Then you need to play somewhere else, possibly earning fewer points now in exchange for a more desired tile for the future.
Each type of the five building tiles scores a different way, but on your first turn or two, they're all the same: terrible. Everything is worth only 1 point when played on its own, but you need to start somewhere in order to build toward more profitable scores in the future, with offices powering the value of future offices and the same being true of subways. (It's easy to peel back the scoring to make sense of it all. The first subway station placed in a town is a huge expense with little immediate value since you have only a single station, so the subway train will just sit there and look pretty. The real value comes from your ability to add additional stations so that more inhabitants of the town can use transit to get where they need to go.)
Two scoring tokens for each type of building are shuffled into the draw piles, and when the second scoring token of a type comes up, everyone scores for that type of building in addition to whatever they scored initially. You also re-score one of the building types in your hand at game's end, so it pays to specialize as long as you can get hold of another such tile later.
Whether a building type will score or not thanks to a second scoring token is mystery, however, since the game ends when two or three supply stacks are exhausted — and in my experience that always happens sooner than anticipated, with players often having planned out another turn or two only to find the game at an end. More thoughts on my five playings of Bloom Town on a mock-up copy from Sidekick Games in the video below: