This was fun! And like any good gamer, die the first time trying to figure out the mechanics, win the second time because you know what to expect! (Context: I died like 2 mins in XP ). This was fun, though my only gripe is how late I got the rifle, but I'm sure on a second run through you'd know to save up for it you really wanted to play with it. I'm not sure if teleportation was a bug or feature, because it seems to happen when I fight the lil guys a lot. I just took it as a feature since it didn't get me killed (;P). I also liked how upgrading health also fully healed you, so I put off upgrading that until I needed to heal.
Good job on this! It was very well put together!