Crazy K: Pick up a total of 1000 passengers.
This is an interesting achievement because it encourages players to pick up as many passengers as possible to get the achievement as fast a possible. Picking up passengers makes the bus heavier, so it is harder to control. This makes the achievement risk vs reward. If the player doesn’t pay attention to achievements they can still get the achievement just by playing the game for a long time. This makes it an achievement for everybody that plays the game, but encourages the player to take risks to get it fast.
Pacifist: Play through all the routes without hitting any pedestrians.
This is an interesting mastery achievement because it encourages a different play-style. Usually the game will reward you for hitting pedestrians from different schools, but this achievement punishes all pedestrian hitting. It is also hard not to hit any pedestrians because of how many of them there are. Players who get this achievement will feel that they have played the game differently and have mastered a part of the game they would normally not pay attention to.