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