I've just updated the game with a few small improvements.

I read a few recent comments from people who wanted to add keyboard shortcuts. Well, here they are!
Pressing '1' restarts the game, while pressing '2' toggles the hint feature.
Escape ('Esc') can also be used to return to the main menu or exit the game.
These keyboard shortcuts should work on all keyboards, so please tell me if there is a problem.
There are also in-game reminders, when scrolling over a button, about which keyboard shortcut can be used.

Finally, there are some small changes to the colour scheme.
Many colours have been changed to be less bright, allowing for a more comfortable playing experience.
Style number 4, the bright yellow colour scheme, has also been removed entirely.
I'm sure nobody will miss it!

Enjoy the game and take care; it's a minefield out there.