Glad to see such a detailed reply! Let me explain some of your points.
1. Sword animations, dumb AI and font. We just had no time to finish it. Creating levels took more than we expected. Each level took 3 hours to build and about a hour to playtest and fix (we actually had 10 levels planned)
2. I totally agree that changing mechanics didn't work the way we expected. For example, at level 2 we wanted player to walk up to first goblin, click LMB to attack and get hit by him, so player would understand that enemies attack by left mouse button. But it didn't work at all.
Next time we want to do more prototyping before implementing the rest of the game to get rid of such problems.
Thank you for playing the game!