Pretty awesome! I only played until the third checkpoint, but it seems like you got a good mix of Castelvania and Shovel Knight in here. The art is very good, but there are plenty of things that should changed. I like the idea of the fists and feet coming out of the walls, they're well telegraphed and are fun to avoid. The enemy designs were good, and I liked the skeletons. It was a pretty nice touch that you could give shakespear his head back too.
The enemies that shoot fireballs out of their mouths shouldn't damage the player from touching him. They don't seem very dangerous, so there's no way for the player to know until it's too late.
The controls are a little weird. I think that spacebar for jump would have worked a bit better. Also, it wasn't clear that I was wearing the shakespear outfit because all I did was enter the inventory to put it on. It'd be nice if you have the player equip it with a button press so that they know that they actually did it.
The design for Ottos is boring. The colours don't stand out well, and if you made him a silhouette he wouldn't be very recognizable. (Take a look at the silhouettes for some of the most iconic gaming characters and you'll see how important it is.) Be sure to give him a good stance and bring out the features of your character. Maybe make him hold the whip to the side instead on his body, have a big hat etc. Also, Ottos seems to old for this girl. Unless she's a goldigger (which might actually make sense considering Ottos is super rich), old people don't date young people out of love very often
This kinda ties into the character design, but the animations are bad. I know you might be going for the 8-bit feel and/or might not have anyone who's very good at animation on your team, but it's super important in bringing the characters to life. I'm pretty sure the walk cycle for Ottos was only 3 frames long, and it doesn't look good. Having bad graphics and saying it's 8-bit still means you have bad graphics. The art for the world is great, animations no so much. Shovel knight is a good example of what to do. The character is recognizable and has good animations, and stands out from the rest of the world with his bright blue armor. There's nothing wrong with give your adventurer a purple scarf or something. It's a video game and your world, so go crazy.
I know it's a demo, but having some sort of tutorial is always nice, or at least teaching the player through doing. You did a good job at that with the wall jump (which needs to feel more bouncy) but not teaching the players how to jump in the first place kinda sucks.
I also feel like checkpoints should heal the player or refill some of the goblet.
You may also want to rethink the general story, or atleast how it is going to be told. Much isn't explained about the world, just how the two characters are adventurers. While the art is amazing for the slideshow, the text moves slowly and nothing really makes me wanna learn more. The girl who I know nothing about goes missing but no one cares except Ottos because all we saw was her just standing around in the cutscenes doing nothing. Also, there was no villain or overarching plot except go see if the girl might be in trouble in Greece. There's not really that much of an incentive for the player to want to learn more. It'd be cool to surprise the player by ending the cutscene mid scene and throwing them into the game, or having the player have more of a reason to go on this adventure.
Just like the animations, 8-bit sounds effects sound bad if you don't put a little more work into them. It doesn't feel good to whip enemies or jump as the sound effects just feel kinda tacked on.
I know it's a lot, but I think it's best if I don't sugar coat anything and just tell you what's wrong. I do think it's pretty cool, and with a bit of work it could easily improve a lot. Remember that the most important thing is that your players are having fun, so if anything gets in the way kill it with fire. You've got some really great ideas and there's some really nice touches, so good luck!
