The results of dice rolls are generated using pseudo-random number generators, which are related to certain numeric values in the operating system. Your opponent knows this and uses it to manipulate the outcome of the dice rolls.

There is a cyclical mapping like this: for example, in the operating system, the number 5 corresponds to a die face of 6, while the number 6 corresponds to a die face of 1, and so on. Keep trying and observe the connections between the numbers.

There are no special rules. Just use your fortune!

Move the cursor to the upper right corner, click the maximise button, and then read README.txt on the desktop. It reveals that there may be some connection between the number on the dice and the current time. Pay attention to the time in the lower right corner.

Click the 'Start' button in the lower-left corner, then open the Debugger. When your opponent takes their turn, don't do anything. Watch what changes occur in the Debugger.

Check your taskbar. Do you see a text editor window? What effect might the number of characters entered in it have? 

After your opponent types characters into the text editor but before they roll the dice, there is a brief pause during which you can perform certain actions.

Check the Start menu. What's there that hasn't been used yet?

In this level, there's no way to freely control the die to show any number you want, and your opponent can't cheat either (so if you are lucky enough, you can beat this level without any trick like in Level 1). However, you do have a way to make the die show a specific value.