Try changing your windows scaling settings to 100% in desktop -> right click -> screen resolution. Log off your account and log back in, and sandstorm should boot up normally. Set the screen settings to Fullscreen. Now you can change your scaling settings back and the game should still work.
This problem only happens if your native Windows resolution is different from the resolution selected in the game in "Full screen display mode".
My windows resolution is 1600X900.
My selected in game resolution is 1920X1080 or 1440 or 4k
(My gaming monitor is 1920X1080 144hz)
The result is the zoomed in to upper left corner display as in the pictures i posted above
This happens because the game doesn't rescale itself automatically in the transition between desktop to in-game mode like other games do.
Most of games is set to 1920x1080 and even if my windows resolution is different it always rescale the games automatically.
If i select in-game resolution to fit my Native windows resolution 1600X900
the game will always load in a perfectly cantered display.
i reported this "problem" back in the Alpha i was hoping it will be addressed in the Beta ... i hope it will be by the launch of the game or in Beta 2