Here is the full list of all 30 Hayfever achievements worth 1,000 gamerscore.
Find secret
Beat Buzzy
Beat Cloudy
Beat Twinkie
Beat Harvey
Beat Hard World
Sneeze 100 times
"Sneeze 1,000 times"
"Sneeze 10,000 times"
Collect 10 letters
Collect 100 letters
Collect all the letters
Find all secrets!
100% completion