The biggest update is the fact that it's November. But aside from that, there's a lot to cover here, so prepare your bones for an even larger text wall than usual.
First off, you gotta give your music people a raise, cos the new tracks for the sewer and the battle tower are a solid 12/10 at least.
...Which unfortunately segways nicely into the bug reports, cos the music is doing some weird stuff with the secret passageways. It fades out in seemingly random secret/layered areas, like inside the pipes in the sewer, inside the big tunnel of water, or if you try and get the chest in the room shown below. That last one in particular is a problem since it muted the music for the entire room, and I had to leave to get it back.
Another small problem with the music is that the battle tower music seems much louder than the music in the overworld.
A final small music nitpick here, but playing the default area music during the new cutscene at the apple boss was a little odd to me, it feels like something that deserves a custom theme.
Let's get back to bugs, cos they seem to have latched onto this update in particular. For starters, the chest in the room pictured above where the music broke doesn't let you open it.
Poor little Melvin the mushroom man now freezes the game if you try to talk to him, fortunately it's not a softlock since you can open the menu and quit.
Unfortunately, the softlocks don't end there. Apparently jumping from the small tree into the spot pictured below softlocks you fully. While the game still animates and runs, you can't open the menu, thus forcing me to alt-f4.
Look at them floating there. So peaceful.
That's everything I found in the old areas, since I didn't spend too much time running around them. However the sewer is a veritable fountain (haha) of traps, as the layering feature sometimes allows you to clip into walls. I've attached pictures of the ones I got stuck in, but there's probably many more.
This one happens basically automatically, just by swimming to the room's exit.
This one occurs via a 3-step program: Step 1 is to get into the water in the part where it switches to the layer with the big tank of water. Step 2 is casually jumping onto the outside of the wall that makes up the tank while still in that layer because that makes sense. Step 3 is to walljump so that the layer switches back and you get stuck in the wall.
And the sewer shennanigans continue. Some of the graphics layering can get a little funky, in particular, the water in some of the rooms renders on top of the soldier instead of behind. Shown below is just one example, but there's a bunch of them scattered around.
There's me peeking out from behind the water. :)
This also made me realise that this game has few if any foreground elements, depending on the amount of work you want to commit to, you might wanna consider adding some in here and there to really spice up your graphics. Examples would be small stuff like plants, flowers, mushrooms, etc, or big stuff like columns, vines, or pipes. Personally I think some foreground leaves or branches in the tree level would add a lot to its appeal, especially in the apple boss room.
Since we're talking about design, another opinion™ of mine is that you might want to make pipes that you can enter look different from pipes that you can't, or alternatively make sure that the only open-ended pipes in the level are pipes that you can also enter. This avoids the Mario Bros. effect of checking every single pipe in the game for secrets, which is especially a problem in metroidvanias where secrets are everywhere.
Something you definitely want to change about the pipes is to fill in the gaps around the edge with black pixels, since for the pipes that don't go to a new layer, you can see the soldier's little feets poking out of the side when you climb up them.
That's enough for the sewer, but the update simply doesn't stop, so let's check out the battle tower now. Thankfully, no issues with graphics or softlocks here, but something that did annoy me was the new stun mechanic. It feels like you get stunned for an unreasonably long amount of time now, especially if you hit the ground and bounce off. If you get hit once by the hellgoat, you get barely any time to jump out of the way before you're instantly stunned again, and I could easily see this leading to a stunlock-to-death if you get stuck between two frogs somehow. If it was up to me I'd just replace stun with something else, like only getting launched a massive distance, and maybe even regaining control in the air, since stun mechanics just aren't that fun. (see Dark Souls.) At the very least you should consider decreasing stun times, or letting you tech off the floor, or both.
Speaking of stun, the ultra-goblin on the last floor is probably a really interesting fight, but I didn't bother to find out, since it still dies instantly to the classic hit them up in the air and get infinite stun trick. This isn't ideal for a boss monster, as we've seen previously. Maybe let them jump away if they're in the air, since they seem pretty agile?
Something you might want to consider, especially if you're making the battle tower have 100+ floors, is mixing up the arenas from time to time. Hollow Knight's collosseum of fools is a really good example of this, it keeps the fights interesting and lets you as a level designer play to the enemy's strengths. It also lets you force the player to switch up tactics, which has been a consistent major weakness of this combat system.
The battle tower is a really good place to find other hitches with the combat system as well. Something I was getting supremely annoyed with was the launch you get if you slide into a wall. It's not useful at all in the normal game, since if you have ground to slide on, you just jump off of it instead, and in the battle tower it meant I would slide to stun enemies, and then not be able to do anything with that stun since I was busy flying uncontrollably through the air.
All that being said, I'm a big fan of the battle tower, even in its current alpha state. Unlike the rest of the game, it actually encourages you to try and not get hit, which is already helping to overcome some of the combat system's shortcomings. You have to get a little more creative than just running headfirst into an enemy and stunlocking them to death.
As a final idea for you, I think part of the reward for beating the battle tower should be the opportunity to jump off of the top of it, and fall all the way back down. It's basically a constant that in games with tall stuff, people have fun jumping off of the tall stuff.
There might be some other stuff I forgot about cos this update is just a little bit massive, but there's already plenty of stuff in my text wall. Hope you had a nice halloween! (: