Sudoku Gridmaster Codes -

Unlimited time:
Press Start during game play to display the options menu. Although the touch screen is obscured, the timer stops. You can then look at the top screen to take as much time as desired to determine your next move. Resume game play, make your move, then pause game play again to repeat.

Earning stars:
Complete the indicated task to unlock the corresponding number of stars.

4 stars: Complete a Practice or Easy puzzle in 5 minutes or less. 
5 stars: Complete a Normal puzzle in 10 minutes or less. 
6 stars: Complete a Hard puzzle in 15 minutes or less. 

Star bonuses:
Complete the indicated task to unlock the corresponding bonus.

50 puzzles: Collect 20 stars. 
Bronze Rank Test: Collect 60 stars. 
50 puzzles: Collect 80 Stars. 
30 Puzzles: Collect 100 stars. 
30 Puzzles: Collect 120 stars. 
70 puzzles: Collect 140 stars. 
Silver Rank Test: Collect 140 stars and complete Bronze Rank Test. 
Normal 141-160: Collect 160 stars. 
Normal 161-190: Collect 180 stars. 
Hard 81-90: Collect 160 stars. 
Hard 91-100: Collect 200 stars. 
Gold Rank Test: Collect 220 stars and complete Bronze and Silver Rank Tests. 
Hard 101-110: Collect 240 stars. 
Hard 111-120: Collect 260 stars. 
Platinum Rank Test: Collect 300 stars and complete Bronze, Silver and Gold Rank Tests.