The combat demo did not come with a tutorial and indeed had barely any playtesting externally.  So here are some things you should know:

• Gravity exists and crashing into worlds in theory hurts you.  asteroid collisions also should hurt, it's just that there's some weirdness going on there I need to hash out.
• X shaped = Drive upgrade
• Rectangle shaped = Weapons upgrade.  Check Gauss/spreader and your railgun for the upgrades as I need to figure out a way to better communicate what that upgrade even did.
• Artifacts collected is atavistic, but it is a fun number to have go up.
• The transparent shapes around or on some players/enemies
• Green projectiles harm shields more 
• You switch weapons with your scroll wheel
• MIRV type weaponry can be remote detonated by pressing down on your scroll wheel
• Yellow/orange (enemy) projectiles harm hull more
• F might do something, it is not the focus of the prototype however.