The Controls in Starblast.io are fairly simple. The ship can either be controlled with your mouse or your keyboard. Moving your mouse around or using the arrow keys will cause your ship to move, while pressing left click on your mouse or the space bar on your keyboard will cause your ship to fire it's weapons.
In addition to the basic movement/attack controls, many other keys on the keyboard (e.g. the "K" and "M" keys) act as an in-game shortcut to chat with other players in real time. Here is a list of those shortcuts:
H = Hello Y = Yes X = Thanks P = No Problem T = Team M = Mine H = Help L = Leader
B = Bye N = No S = Sorry G = Good Game W = Follow Me A = Attack K = Kill Q = Hmm?