If you're on windows, there should be an option for 'more info', after you click that the 'run anyway' button should pop up
and as the comment under me stated, the game unfortunately can鈥檛 be played on mac. Whoops. I know nothing about mac 馃槄
A lot of people have had the issue of the screen being awkwardly casted to the corner upon opening the game, including myself. I managed to fix that by pressing esc to reveal the cursor, resizing the window until I could see the bar on the top and then fullscreening it by pressing the fullscreen button. Hope this helps anyone with the same issue! :D