With Steam's Next Fest over halfway done, what demos have you played and enjoyed most?

Copying my previous comment and also adding some more games to it:

I liked:

• Viewfinder – a puzzler reminding me of superliminal
• Let's! Revolution – an interesting mix of minesweeper and a rougelite
• Sea of Stars – an RPG, with turn-based combat but with traversal similar to CrossCode. Not much of the story is revealed in the demo, but the characters were interesting
• The Cosmic Wheel Sisterhood – "a narrative experience" (somewhat of a VN with more interactivity) where choices matter. Hard to judge how good it will be based on the demo, but I liked the vibe.

And an honorable mention to a demo that was already available last time:

• Escape From Mystwood Mansion – a room escape game

I gave a bunch of stuff a fair chance, most came somewhere out of the puzzle category

On my pickup list:

• Viewfinder - 3d perception puzzles ? count me in
• Jumplight Odyssey - space ship management with loads of influences including FTL; i just hope this gets the time to iron out its kinks
• Escape From Mystwood Mansion - escape room game
• He Who Watches - dungeon crawler with puzzle elements; being bound by movement
• Cipher Zero - there is some great stylized art hidden between the minimalist logic puzzles; wondering if this goes anywhere else
• Lil' Guardsman - a humerous papers please
• Crime O'Clock - a bit of MicroMacro with some time travel

maybe:

• Venba - some mild cooking with a heavy story orientation; not a lot of content in the demo
• Stunt Derby - seems to have the classic stunts as a heavy inspiration; not there yet but i would give it a second chance in the future

not for me:

• Pizza Possum - running around without being caught didn't click with me
• Heretic's Fork - card based tower defense
• Logic Town . deduction puzzler that got stale very quickly
• WASD Quartet - more of a 1 minute experiment then a demo of anything, still find it lacking in the sound departmend even though its thythm based
• Crazy Zen Mini Golf - the mini golfing doesn't feel tight enough; controls seemed off

I really enjoy next fest a lot, still so many more things to give a try.

Stuff I liked:

• Viewfinder: My favorite demo of all of the ones I played. A really neat puzzle mechanic that seems well implemented with lots of creative variations.
• The Invincible: I was interested in this one before the demo, but it wasn't quite what I was expecting. It seems to mostly be walking around, examining things, and listening to conversations between the player character and someone else. The graphics are quite pretty and it seems like the story will be good, so I will probably take a look at it at some point in the future.
• Crime O'Clock: An interesting take on the hidden object genre where you have to examine a sequence of scenes from an event to solve a crime.
• Cipher Zero: A simple puzzle game with a neat aesthetic. New mechanics are introduced in a way that makes them intuitive by the time another one is introduced. Some puzzles have multiple solutions, and each one is counted for full completion of a level.
• Kanji Industry: An automation puzzle game where you build Japanese letters from their component parts. Needs some serious polish, but it is an interesting concept.
• Cuisineer: A game where you inherit your parents' restaurant. You need to explore dungeons and kill monsters to gather ingredients to make food, and complete quests for people in town to earn recipes.
• Word Factori: A similar concept to Kanji Industry, but with more polish. You build English letters and words using only the letter "I" as a base to work with.
• Little Kitty, Big City: Great animation, funny characters, and lots of little things to do with the end goal of returning home.
• Station to Station: A puzzle game where you have to connect various buildings with train stations to create a complete network of supply and demand.

Stuff I didn't like (or at least not enough to buy):

• Sea of Stars: The art was very pretty, but the gameplay just didn't capture me for some reason. It seems like the demo takes place somewhere in the middle of the story without providing any context, making it feel like you have just continued someone else's save file in the middle of a game.
• Pygmalion: The puzzles were fine, but it got a bit annoying to constantly have the gameplay interrupted by story, and the story constantly interrupted by gameplay. Maybe it would have felt better if there were large story chunks at the end of a set of levels instead of a few sentences after every single level. It probably didn't help that the demo only shows the first 3 sets of levels, which are probably the easiest in the game, all able to be solved in just a few seconds.
• Cardbob: The aesthetic of cardboard robots is cool, and using the trailing bandana to show remaining HP is super unique, but the gameplay felt a bit generic and I could never find a way to survive the room immediately after the first boss.
• Robotherapy: Very funny story, but that's about all it has going for it.
• Tiny Room Stories: Rift Escape: This one was pretty good and seems like it has an interesting story, but I ended up getting stuck in a room for about 10 minutes before giving up since there was no hint option available in the game.
• Broken Lens: A spot the difference game where you play as a robot with a broken lens in one of its eyes. The screen is split into two halves, and you have to click and drag to explore a scene to find discrepancies. It has a hint function, but none of the objects are randomized in the scenes, which trivializes the gameplay if you don't feel like finding the objects yourself. I liked how there were hidden papers in each of the levels that had a little bit of lore in them.
• Street of Secrets: Another hidden object game, the gimmick of this one seems to be that the objects are hidden in multiple rooms within a house that you have to navigate between. Nothing really wrong with this one, it just doesn't stand out to me in any special way.
• One Lonely Outpost: I was previously planning on buying this one, but the demo convinced me otherwise. Terrible inventory management, the days are too short to do anything meaningful, and there is little explanation of what you are supposed to do.
• Lovux: A neat puzzle game, but the music got really annoying really fast, and the animations for interacting with things took a long time, making a large part of the game just waiting for animations to finish so you can click on the next thing.

Liked:

• Lost Chapter: an 18+ hentai Slay the spire clone. It's been out for a while but didn't have an official english translation, which will come with the Steam release. Nothing groundbreaking here but it seems worth picking up if you enjoy the art.
• Absorption Battle Racing: another 18+ hentai title, this one's a racing game. The tutorial leaves a lot to be desired and with 30 characters per track it feels like a total clusterfuck... but I think the animations are well done & the characters look good - and that's what matters most.
• Trepang2: If you played F.E.A.R., this game's for you. The combat is really, REALLY good, but the story, setting and characters seem super barebones. Game has come out already during the event and is getting 90%+ positive reviews.

Disliked:

• Heretic's Fork: a tower defense card game. I was super confused on what to do after the first few rounds, there's a bunch of unique mechanics like only having 2 tower slots, starting towers with super unusual attack patterns or the way you're supposed to sacrifice cards to cycle them.
• Acolyte of the Altar: A lovecraftian Slay the spire-ish roguelike card game. Love the visuals but there was nothing unique about the gameplay that made me want to keep playing.
• Quasimorphosis: A singleplayer turn based extraction shooter. This one has NO tutorial currently and so I was completely lost trying to figure out how to correctly approach combat. Kept feeling like I have no idea what my opponents are capable of, when I need to take cover, how to ration healing items etc. The combat seems super simplistic as you have no abilities to use.

I think the only one I'm sticking around for is House Flipper 2, even though it was extremely buggy for me. I tried a few other ones.. nothing really stuck, to the point I can't even recall the names of the games.

Sea of Stars is the only game that seemed to resonate with me. Maybe I'm old, but the game seemed to push all the right retro RPG buttons.

I've been enjoying the Warhaven demo a lot. TBF, it feels more like early access instead of a demo though. Bookwalker was pretty interesting too.

Fortune's Run is a lot of fun. Like a mix of Deus Ex + boomer shooter with retro graphics.

I'm absolutely in love with The Cosmic Wheel Sisterhood

I've already replayed the demo several times. Definitely not everyone's cup of tea, but it's absolutely in my wheelhouse and I'm super excited for it.