EMRYS0821  It's in the iTunes App Store.  
(Version 3.3)

EMRYS0821  I have the same problem when I disconnect my external monitor.

I use a MacBook, connected to a 20.1" Wide-screen LCD.

Instead of using both screens, I utilize the hardware feature where I can close the lid and the main screen will be the attached monitor. I prefer this over having two screens.

I consider the way I'm using the app as "unconventional", so I've never bothered the developer about it crashing once I disconnect the external monitor.  
(Version 2.0.3)

EMRYS0821  I made the mistake of updating to v.2.2.2 when I got the new "VX Nano Cordless Laser Mouse for Notebooks".

It's an awesome mouse, the software/drivers (Logitech Control Center) are just terrible. Running 10.4.10 on an MacBook and I would get at least 2 - 4 Kernel Panics a day when I had the software installed.

Read the reviews here, and read Logitech's Mac forum, lots and lots of Kernel Panics.

Check out "USB Overdrive" or "SteerMouse" as alternatives. It's just too bad that you have to pay around $20 extra to make a Logitech product work, when it should come with stable drivers.

If you require the software to get your Logitech keyboard to work, I feel your pain.  
(Version 2.2.2)

EMRYS0821  "There's no undo function to take back a wrong tile placement, no pause function, no difficulty level to choose from."

Look at the Options area. Escape is the default pause. You can change it to what ever key you want.

I agree on the undo function... that would be nice.  
(Version 1.0)