Here is the full list of all 22 InfiniPicross achievements.
10 Continues in a Row
10 Solved
5 Continues in a Row
5 Solved
One Continue
Set a Seed
First Solve
3x3 or Bigger Completed
5x5 or Bigger Completed
10x10 or Bigger Completed
15x15 or Bigger Completed
Change Theme
25 Solved
50 Solved
100 Solved
25x25 or Bigger Completed
50x50 or Bigger Completed
99x50 (or 50x99) or Bigger Completed
Reset a Filled Grid
Create a Theme
Use The Workshop
A Certain Familiarity