First of all the polish on this is astounding. menu, music, graphics, gameplay are all good quality.
The concept is original. Reminds me of starlord's adoptive father in Guardians of the galaxy.
As some have pointed though, the syringe is really hard to handle. The furthest i got was using it as sword pivoting it around with my character on top. Having to "refuel" the syringe is getting me killed times out of ten :)
As a mechanic, that last one got me ambivalent : i see that it gets the player to strategize and anticipate for your syringe to expire, but it's really harsh...