What is “New Game  F2”?

It is used to start a new game in the same practice mode played last time.  It's there for your convenience when you want to play several games in the same practice mode. It does not apply to Email mode or Challenge mode.

Sometimes I can't start a new game by press shortcut key such as F2?

You can only start a new game after you finish or quit your current game.

How to quit a game?

You need to press ESC key or “Give Up” button. You'll be regarded as losing the game in most modes except Email mode in which you just quit the game.

How to play “USER vc USER” mode with one mouse?

Another user can use keyboard. Keyboard is also supported in single user mode.

I can’t change some options such as rules and levels in some occasions?

Once the game starts, you are not allowed to change rules and levels in the middle of the game. Also challenge mode will have preset rules and PC levels and those will override your options.

It says “Illegal Position” when I try to place a stone?

You must be in advanced rule. Please check the Rules.

I can’t use Undo/Hint in some occasions?

It can be one of the 2 reasons:

1. They are not supported in the mode you are in especially if you are not in practice mode.
2. You used up your Undos (normally 5). Only “USER vs USER” mode doesn't have limitation.

What’s the difference between “Save Game” and “Save Position”. 

Save Game – save to a text board file can only be replayed but not continued.

Save Position – save to a text board file can be both replayed and continued from its last position 

There is no attachment in the email?

Some email clients can't attach the email game file automatically. If that's the case, you will need to manually attach it. Sorry for the inconvenience. I'll try to fix it.