Here is the full list of all 12 Gnomes Garden 7: Christmas Story achievements worth 1,000 gamerscore.
For clearing one roadblock
Recruit 50 or more workers
For constructing a building
Banish 100 or more gremlins in a game
Recruit 50 or more merrymakers
Collect 50 or more sorceresses in a game
For speeding up workers
For stopping time
For speeding up construction
For completing all levels with 3 stars
For collecting all rewards
For creating a Christmas tree