i am sorry, i dont think i can you help coz the game is played in fullscreen by force
(usually, with unity games, there is an small window that opens before the game opens where you can set the resolution and what not, sadly, i dont think they enabled that option when exporting/building the game)
one suggestion i have is setting your desktop's resolution to something higher, like 1600 x 900...etc (you can do this by right clicking in the desktop and select "Set Resolution" on windows 8)