Here is the full list of all 20 Graveball achievements.
Complete the tutorial
Win a game
Win 25 games
Win 100 games
Customize your goblin
Score a goal
Score 3 goals in a game
Score 5 goals in a game
Score 100 career goals
Score 1000 career goals
100 career kills
1000 career kills
100 career saves
1000 career saves
Win a game without allowing a goal
15 kills in a game
25 kills in a game
Save a goal
3 saves in a game
5 saves in a game