really cool - the environment / world feels good - and so do the enemies!
though maybe some guidance at first would be great - i know linear isnt something youre going for but for a demo it would help.
i would add some varience to the way the shield enemies attack. they run in a straight line - they could surround you and slowly circle in instead of running at you - or something like that
the game needs more juice, interacting with things should give more response, ex: shooting walls, enemies with shields (they still bleed, even tho they take no damage from the front),
some design choices could be looked at - the shield enemies dont have shields that cover their legs so i shot them instinctively in the legs - but it did no damage. maybe extend the shield, OR add an animation where they crouch slightly to cover them whenever they get shot at
killing civilians (or scientists - not sure) is fun