Major upgrade to your last game. I think it's a very solid short game. There are still a few bugs to work out in terms of movement, collisions, and sound. I think if you fixed some of those issues as well as added a few sound effects into the game for when the player jumps, attacks, dies, etc. it would be better. For right now though, it's a solid game that can be improved upon. I did a Let's Play of it here: https://www.youtube.com/watch?v=LVqZ7kdrbQk&feature=youtu.be where you can see some of the bugs and issues I encountered. I enjoyed the game though, keep it up.
The lag seemed to be from something other than the game (though I encounter partial lag each time I play it for some reason but it varies from extreme to nearly nonexistent), but the sound when talking to the "instructor" or whatever he is called always seems glitchy and I don't know if he's supposed to talk or not.