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