If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
The Last Stand
Mouse - fire.
R - reload.
Space - swap weapons.
During the night you must stay vigilant and protect your barricade against the oncoming hordes of Zombies. Manage your time during the daylight hours to great affect searching for weapons, survivors and to repair what was broken in the night. Good luck surviving!