Concentration 1.0.0-4

What's new in 1.0.0-4
Improved keyboard navigation through the game board and main menu.
Fixed Enter and Space selection for the initially focused card.
Improved keyboard focus highlighting when moving between the game board and Exit button.
Added fullscreen toggle support through the menu and F11.
Escape exits fullscreen mode.
Installation

Download concentration_1.0.0-4_all.deb from the Assets section below and install it on a compatible Debian or Ubuntu system:

sudo apt install ./concentration_1.0.0-4_all.deb

Full Changelog: 1.0.0-3...v1.0.0-4